I have a 1997 Ford Ranger 4cyl 2.3L motor. It has about 104,000 mi on it and it has been maintained quite well since I've had it (bought it when it had 80k).

Recently it broke down on the high way. It sputtered in idle and would stop, when I would get running to move forward it would only do so for a short period of time and then die. I ran an OBD II on it from the Autozone across the street and 2 codes came up P0171 and I forget what the other one was (should have written it down I know). I changed the fuel filter out thinking it might be a fuel problem but it did not work. I had the vehicle towed to a shop where they replace the MAF sensor. The shop tested the vehicle with the new MAF sensor and the MAF shorted out. They then put a new computer in the truck (new one with the correct software from the ford website) and an additional MAF sensor.

As soon as I drove it out of the shop the check engine light came on again. I took it back and the code P0171 showed up again (and was the only code). He said it might be due to the very cold weather (Chicago area). He said to bring it back if it still has problems.

I've already spent $650 getting it fixed.

The truck ran fine for about 150 miles and now it is doing the same thing again. The mechanic checked the truck and said the fuel pressure was right. What could this possible be?

 

Check your vacuum and PCV hoses. Vacuum Hose Guide

Also have you changed the O2 sensors? I believe this is supposed to be done at 100k Miles.

 

po171 from everything ive seen is a lean code...I really doubt a o2 would throw lean..I would think rich if anything...but I would DEF check for Vaccum leaks...as thats probably what the problem is