Snorkeled water, flooded engine, still kickin cause she's a toyota but..

About a month ago I tried crossing a flooded road that dipped down deeper than I anticipated (I hopped out to push at knee level). Naturally my engine died. i got towed out and down to my house by a neighbor. I looked at it the next day, removed the saturated air filter and checked the oil and it looked all fine, only a slight amount of water in the air-duct. I slowly got her started, cranked over but she dies at idle, poor idle performance, low rpm's, etc. Checked the oil and it was all coffee. Changed it immediately. It ran better after the oil change but still not able to stay running at idle (except for a few times after a long drive, for a few minutes at a weak rpm/idle)

A neighbor suggested I dry out the distributor, as 'steam' can get in there sometimes but you know it is popping that side of the 'hood' so I'm saving it for fair weather (and a igniter/coil swap to eliminate a misfire). The check engine light will occasionally turn on when I'm coasting at a steady RPM's then shut off as I alter the rpm's a bit.

I originally thought it was the TPS/Mass-Airflow since those part are in-line with the air intake.

using this website's guide on engine lights I have 5-5, or "oxygen sensor" "OPEN or short in Oxygen sensor signal (only lean or rich indicated) the diagram suggest 1)O2 sensor circuit, 2) o2 sensor, 3) ECU.

O2 sensors are ~$25 and most likely the culprit since it was under water but i was wondering if there is anything else I might consider before just replacing it. I'm a bit tired of replacing parts left and right only to realize there was something else to consider first.

Gas mileage hasn't changed much. I was getting a low 19-20mpg for awhile, pretty consistently (gonna address that misfire to get mileage back up hopefully) and that's what it is most the time but the last tank was up to 22.

I would have the engine compression checked to make sure that you did not partially hydrolock your motor and bend a valve or bend a connecting rod. If the engine was comprimised in any way. no point in looking at 02 sensors, distriubutor caps, rotors and plugs as none of those things will help if there are any bent or broken parts.

compression check first

Then an oil pressure gauge. the oil looked OK because you saw the top. oil floats on water so the water was down by the pickup. you MAY have washed out the bearings and bores before the water-oil emulified (milkshake).

The O2 sensor could be bad... or a nick in the wire anywhere from there to the ECM went from hanging out to a short or corroded.

could be anything (or everything) electrical from the sensors to the ECM itself.

It was a crack in my Intake boot. I had inspected it twice over the past year and didnt see it along the seam. Yesterday I went to pull it off to change the filter and it ripped apart. I pulled another from my other van and it ran like normal. I also sprayed some lectra-clean on the airflow sensor door but feel the boot was the primary problem. Adjusted my idle back to 750 like the book suggest and its running great.