Guys, a good quick test is to disable the MAF, then see what the trims do. If they go down then the MAF is the culprit, if not, time to look elsewhere. A dirty, or modified MAF can throw its calibration off.

 

That's what we did, and that's what happened, which is why we're focused on the MAF sensor now.

 

My truck was running with 13.0 afr at idle and 11.0 afr cruising even though pcm gave me a lean code and high level fuel sender code. I plugged in a scanner and noticed bank 2 was reading 25 to 50 fuel trims. I switched the O2s to apposite sides and the codition followed over to bank 1. Tonight I replaced the bank 1 o2 and it is running normal again with 14-15ish idle and cruising afr. Have you ruled out the o2s.

 

Yes, they are ruled out.

Trims run parallel, bank to bank. They increase with engine load and RPM. They are not an issue with MAF disconnected. Really leaves 2 possibilities. Big intake leak, either pre or post TB, or bad MAF.

 

justin I PM you on SSS.com and thunder hit you up here on PM. I hate the dealers but I did get a new cluster out of it but thats another story.

 

I had the same problem. I replace my intake manifold gasket and that fix the problem.
I hope you got it fixed?