Tuning Issues

[moehorsepower]

I need some help.I tune supercharged LS and LT1 cars but this is the first time on a 02 Burb with a whipple charger.The whipple computer was removed and tuning done with LS1 edit.The burb has 38 lb Delphi injectors a 6.0 litre that has a mild cam.The Problem:IT made 408 RWHP with an 11:8:1 A/F.The lower driveability is terrible,runs like a 4 cyl untill around 2500 RPM then it goes.The LTFT are at between -.78 to -1.5.Timing starts around 25 degrees at the lower GMS/CYL and then maxes out to 11-12 degrees.No Knock Retard at all.I have tried everything with no luck.Also when the new injectors were installed of course it ran rich,after setting the IFR it was fine for awhile then it started leaning out bad,Could not get the A/F to come down.Then it got rich again around 10:0 after about a week back to the lean side.Has new MAF,New o2's.It seems no matter if I add timing,fuel no results.Torque management it removed also,Anyone with any ideas ?

[RedHeartbeat]

Not pcm related but have you confirmed the fuel pressure? May be way too high, too low or not regulated at low rpm/low boost and flooding out the engine with too much pressure. Too much pressure is almost as bad as too low of pressure.