[Kyrasis6]

That can be a very complicated problem depending on what the problem is or was originally and what has been repaired and how it was repaired. For instance the truck goes without a tune up for a while and the air filter gets severly plugged, the lack of air causes the fuel mixture to richen. The computer tries to compensate by leaning the adaptive learning fuel trims. Later you give it a full tune up and it runs like crap and the check engine light comes on, you take it to a mechanic and he can't find anything wrong with it but he looks that the sensor outputs and it says both upstream O2 sensors are reading lean. He doesn't know what it is so he tells you to replace the MAF sensor and it still has the problem. The mechanic could have very well not even looked at the fuel trims or possably not known what the heck they mean, as many mechanics don't and therefore didn't know what was going on. If he did know what was going on he would have reset the adaptive learning and taken it for a road test to run it through a drive cycle. Problem fixed.

I don't know what has been done to the truck or if the mechanics you took it to knew what the where doing. I think the first thing I would do is have the ECU reset and drive it through the relearn procedure and go from there.