I have a 2004 Comp G. 2 weeks ago i started having a problem. The car would run great, but when i would hit it to pass on the road, it would stutter and the check engine light would start flashing. As soon as i got around the car and went down back to speed, it would stop flashing and go out. So, i changed the plugs, wires and coils. Now it acts like it has no umph like it doesnt want to go and the check engine light is on constantly. Can anyone tell me what could be going on? I am at my wits end. THe car has 138k miles on it. Thanks all.