Excessive Fuel Consumption and Power loss after doing work on the van, where to look?

The issue I am having is sub par fuel economy (10-15 mpg when it was getting 20+ when I bought it), no power or torque (my driveway is a tiny hill that Tiny Tim could climb without crutches and when I tried to go up from a dead stop I got nowhere even with the throttle to the floor, seriously I didn't budge and inch and my top speed downhill is 40 and going up a slight grade I might hit 20). I believe the AFR is on the rich side because on my way back from my mechanic (he does stuff when I have no time) my muffler to my cat were cherry red causing me to cut open the clogged muffler (inside was rusted to hell) which alleviated the heat issue for the most part but turned a quiet van into a trumpet.

A bit of Backstory
I bought this van back in September of 2016 from an Asian guy named Thor who drove it off the show room floor and kept it rust free all the way from California to North Carolina. I then promptly drove it back to Harrisonburg Va and began replacing every thing I could think of that hadn't been touched in the past 243,000 miles. When I got it originally it was mechanically sound and made it up mountains and highways between 60-80 mph for several hours. Only thing I couldn't get to work was the AC but for $1000 for a well running van with 4x4, no rust, and captains chairs who could say no? Well... besides the fact that if you turned the floor vents on in the back while the van was on it would fill with fumes..... so no AC and open windows til I get home. *EDIT the engine has never been rebuilt but the compression test came back with good numbers.

The "Mechanicing" Part one

First thing I noticed when I got it home was a leaking power steering line (between the pump and the steering box and I swear it wasn't leaking when I bought it) Replaced it immediately and rather painfully over 2 nights after work and that is all good right now. I also replaced the line from the pump to the reservoir because it was rock hard. I have yet to dig into the rest of the line because of where it is but as of now the Power Steering System works perfectly and the fluid is all new

Next I got around to replacing the fuel filter while I had the passenger panel out. (It was a TOYOTA ORIGINAL no joke I was surprised) Went in with a bit of effort and cursing. I don't believe there are any leaks because the fuel tank holds pressure for days when the van hasn't been run (is it supposed to do that?)<br><br>Third thing on my list was every vacuum hose I can find. Which went Ok til my friend touched the PCV valve at which point it turned to dust and fell into the valve cover. It took 3 wedges and a hammer to get the damn valve cover off because it was that stuck on (no we didn't bend it). We then replaced the valve cover seal, cleaned the oil off the top and the crud from inside and replaced the PCV Valve and gasket. It was at that time that I noticed that the little yellow plastic thing in the Idle Air Control Valve was broken off. I am just now ordering the parts to replace it. The rest of the hoses went on fine except for the biggest shortest one towards the front of the engine. That one still has a slight kink in it.

After that we buttoned everything up and it idled like crap when cold but once warm it was just fine.

Part 2

We popped the seat and discovered the the bi metal switching valve had broken the 2 hose barbs off and the 2 electrical connectors that I assume check coolant temp had also disintegrated. I ordered a replacement BMSV off Ebay for a different vehicle that used the same Part Number and I ordered 2 female plugs (same type as injectors). I spliced them in and so far that seems to have fixed the idle issue.

The "inspection"

So I take it to the mechanic who does the work on my work vans and they have never seen one of these before (GREEAAAATTT) They proceed to give me a laundry list which included wheel bearings in the front, wheel cylinders and soft lines, exhaust leak, headlight too dim and other trivial stuff. Mind you I have no grinding or vibration or any other things that might clue you in on bad bearings so at this point I believe they just wanted to charge an arm and a leg to do them.

Garage Day Part 3

So at this point I've repaired or replaced all the minor stuff like wipers and the headlight. So I decide to tackle the soft line and both wheel cylinders. *The brakes had no travel to stop before I touched them* Once we replaced both cylinders and a soft line (that looked in better shape than the new one) we bleed the brakes for several hours have no pedal til the floor and tons of bubbles. After 2 days and 2 quarts of fluid I'm out of time so I drive it to my mechanic who works at a dealership but does side work for friends.

He proceeds to back feed the brakes and we finally have pedal. However now the car is losing fluid so we are going to replace the master cylinder and booster because its not leaking anywhere else...

The main reason I took my van to him was to pull the manifold to replace the gasket so I wouldn't die if I turned on the rear vents. This turned into him: completely replacing the manifold because it was cracked on 3 runners, replacing a broken manifold stud on the block, doing the belts, new toyota brand thermostat, and the hose of death.

After it was all together it ran like crap and it turned out that injector number 2 had failed. So he tears it down again and I sent him reman Toyota injectors from a guy out of FL. I then had him replace the plugs and wires. The distributor cap looks newish (brown in color and no oil on it so....) It runs better so we figure thats it.

On my way home we noticed the muffler was spitting flames so we cut it open and dumped a ton of rust out. It continued to shoot flames every time the automatic transmission would shift. I was only able to hit 30 uphill and I babied it at 55 on the flat part of main road back. I used 3 gallons of gas for 40 miles of driving back.

After that I parked it 2 weeks ago while I waited for a new muffler. I finished attaching the muffler yesterday and I took it for a test drive. I was only able to hit 35ish if I had my foot to the floor. It sounded like I was driving a lawn mower. I drove maybe 2 miles and then parked it at home.

I have checked the vacuum line connections and all the plugs. The lines were where they needed to be but I am ordering new injector plugs because the old ones are rough. I have pulled the throttle body and I am cleaning it now. I am replacing the original Throttle Position Sensor as well as the IAC and the throttle body gasket. I pulled the flexible hose for the intake and checked it and it is without cracks and isn't vulcanized. As far as I can tell the TPS was physically good until I took it apart and broke plastic but I can't speak to its resistance.

So in essence what could cause excessive fuel consumption and massive power loss? The CEL isn't on but I haven't jumped the code pulling connector so there may be a code in the system. I will update tomorrow night when I do that. Its raining too hard to do any more work. If you've gotten this far, thanks for the help. I'm completely stumped with this van.

Alright, so last night I pulled the Plenum to get at the injector harnesses to replace them. In the process I found a broken vacuum line going to this sensor that has a coolant intake off the back of the engine and an outlet into the throttle body. Anyone know what that sensor is called? The Toyota part number on the plastic says 22230-73011. It has 2 vacuum ports, 2 coolant ports, and one electrical connector all mounted under the plenum.

Oh, and when lifting the plenum up to disconnect the coolant hose from the plenum the metal on the T joint on the block fatigued and cracked at a joint. That should be a fun one to find a replacement for. Wish I knew what the part number was.

Figured out what the sensor was. Its the auxiliary air valve. Wonder where I am going to get that because Rock Auto is out.

salvage yard. sometimes googling the part number gets good results

Could always try JB-Weld to seal the joint. It's what is holding my one of my valves together.

Fuel consumption in a gasoline injection engine is determined by:

1) Injector flow
2) Fuel line pressure
3) How long the ECU opens them for (influenced by temperature sensor)

As you fitted new injectors you may want to check they are of the right type.
You should be able to get a fuel pressure gauge, or just renew the regulator if cheaper.

IMO the tank should not be pressurised, that might also force more fuel in - it should vent through the fuel cap IIRC.