I have a new issue that just popped for my 2004 grand prix gtp. Was driving a few days ago and these codes popped P1125, P2120, P2125, P2138 and P0401 w/ no performance problems. I cleared the codes thinking it was false error and car ran fine for next 3 days until today when my RPM began to dip an drop at idle and even when accelerating first I thought it was bad gas since i filled up at a new station and put a can of seafoam gas treatment in. Seemed to run better for a few mins. Then I got on the freeway and engine light, traction control and "reduced engine power" light came on and noticed the accelerator pedal began to feel funny before car shutr off. I scanned codes and only received P0068 and P0101. Any idea what I should repair/replace? Trying to save money w/o taking to dealer. I replaced the EGR valve and had the valved tube cleaned and still get a light.Thx in advance.