I have a 2001 2500hd 8.1L. My message center says reduced engine power. Truck has a p1125 code set. Truck won't even make it out of the driveway without the message coming on. Can let the truck idle for hours with no faults. Step on the gas a couple times and you get the message. I am about to start beating it with a hammer. I have changed the APP sensor. The TPS sensor. The TAC module. I replaced the ground on the rear of the left head. I have checked for loose/broken wires At the app,tps,TAC module, and throttle body. Anyone have any ideas on what's going on or what I could try next? Thanks chris.