Quote Originally Posted by Fast355 View Post
Sounds like low fuel pressure, unmetered air leak or a dirty MAF to me or some poor WOT tuning masked by closed loop at WOT.
I'd like to point this above right on post out. The MAF meter is probably almost 20 years old. 90% of the new/rebuilt ones are sometimes worse than the dirty/coated one you take off. There is no reason EVER to have to alter the transfer function of that MAF in the calibration. Are we smarter than GM on this transfer function? That type enclosed MAF with screens is dead nuts and reliable till it gets dirty or typical age ozone and dust coated. The only ones you can buy that seem to be correct are the AC-Delco and Delphi NEW maf's, not the rebuilt junk at NAPA, Oreilly's, Autozone, etc. You said you have a stock engine so unless you made changes to alter the VE(exhaust, cam, porting, etc), your VE table should be pretty right on too. Best thing to do to start is turn off VE and get it to run correctly on just the stock MAF settings.
I am not talking about cartridge MAF's and how they are critical to inlet ducting and any change in that can cause a lot of grief.

LRT has been very kind to help you, chasing failing or just bad equipment doesn't help anyone.

Good luck,
-Carl