I have a 2004 Pontiac Grand Prix GTP with about 140k miles on it that goes into reduce engine power mode occasionally. I think it only does it going up hill, but not every hill. Repair shop said throttle body $900. I replaced it myself as well as the accelerator pedal sensor (due to the codes that pop up) and I am still receiving the same codes. (P1125 and P2138)
What should be my next step?