Apologies if this has been covered, I tried searching several threads but haven't seen my specific problem. Particularly at higher speeds, my '85 5-speed van loses power the harder you push in the gas pedal. To get it to run smoothly and with any sort of vigor you have to have the pedal barely pushed down and when going up hills sometimes even with that it drops down to 45-50mph. Fuel filter was my first guess. Hoping for something I can handle myself, but recommendations for a mechanic in the Portland area would also be welcomed.