VERY good chance that could be a factor. But based on he pulled the MAF and it worked better on default tables means there could be something wicky about the MAP, PCV, and/or EGR?
[TRADED] 2005 Grand Prix Silver
K&N Air Filter, NGK TR55GP G-Power Plugs, Delphi OE Wires, Timken Bearings, Mobil 1 Synth ATF & Oil, Purolator PureOne Filter