Oh ya and clean the maf. As stated above it can cause a lean ping under load. Should be cleaned from time to time anyways. It gets worse if you have some sort of after market air filter that you oil. Oil can stick to the sensor followed by dirt.
Some thing else I read was certain CAI's have funny bends that redirect the air flow over the maf in such a way that it gets a funny reading. What kind of air intake are you running. Just a thought. I have no proff my self of this causing the problem.
Once again Good Luck
Ill probably re clean the maf sensor again. I cleaned it last summer. Im running totally stock engine..stock replacement air filter, Im should have mentioned Im running safe way 87 octane gas...probably not the best I know...