No power in the top end
 

My neighbor has an 03 lb7 with a CAI, 4" exhaust, and a bully dog programmer. When you goes to get on it, around 2800-3000 RPMs, the truck just dies. Then until it shifts it's completely gutless. What could cause this? Is it just the Bully Dog de-fueling it before it shifts?

u limp it out what codes do you get

No real good idea, just something I found- my 01 was falling off really bad just like a defuel. Got to looking and found the fuel inlet line at the left rear of the engine had a bad kink in it. New GM part (the fuel line) that runs from the tank goes over to a bracket on the trans then forward is $415. I cut the bad flex hose out and replaced it.. cost $10

My truck did this and I replaced the fuel filter. That fixed the problem. Is it shifting ok? If not then you might want to try replacing the spin on the trany:moon: