You are flooding the engine with fuel when you step down the pedal, and that stalls the engine. This is probably because your car timing is behind. A good tune-up and adjusting your ignition timing will solve this problem.
Start with replacing the fuel filter.
idle control sencor
start car pull up hand break tight put in to first gear and lift cluch pedal as if your going to drive take your foot compleay of cluth pedal with the hand still on if the car stalls its ok if it keeps running u got a problem
If your 2003 Grand Am accelerates without pressing the gas pedal, the throttle plate may be stuck.
If the engine is running it is burning fuel, whether the gas pedal is pressed or not.
tps throttle position sensor
It is on the accelerator pedal. You have to replace the whole pedal assembly
when kick down the gas pedal to accelerate, the car downshift but then stalls and then engine stays rough until i turn off the engine and restart it then the engine runs normal again till the next kick down.
on top of gas pedal
Check the sensor on the brake pedal arm.
I've had this problem a few times with my 1996 cherokee. The first thing which was replaced was the CV valve, and it was fixed for about 5 months, and then it started happening again about a month ago. I'm a college student on my own, and could not afford to have it fixed immediately, but I did drive the Jeep into town yesterday to have it looked at. The mechanic said the throttle sensor was broken, so he replaced it and it's been running like a champ since. I always forget how much power that 6 cylinder 4.0 high output engine has!
How do i fix the TPS pedal position sensor in a grand prix pontiac 2004.