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Grand prix issue

I have a 2004 grand prix. Earlier this week my car started to reduce acceleration. So i pulled over and turned the car off and yried to start it but wouldnt start. I ended up replacing the alternator. The car started working fine again. Then today i was on the highway and the reduced engine power came on again and i couldn’t accelerate anymore. I had to coast off the highway. I turned my car off and sat for a minute then started it up again and then i was able to push the gas once agaun and drive off. What could cause this?

There may be a problem with the accelerator pedal position sensor.

https://www.rockauto.com/en/catalog/pontiac,2004,grand+prix,3.8l+v6,1429703,interior,accelerator+pedal+position+sensor,5061

Instead of having a throttle cable from the accelerator pedal to the throttle body. your vehicle has an electronic throttle body.

The accelerator pedal position sensor sends a signal to the computer, and the computer operates the electronic throttle body from that signal.

Tester

Crankshaft position sensor

I have a 06 Grand Prix and have had this issue , trust me you are going to go Thur 100 things trying to figure this out , due your self a favor go get the sensor for 50$ , a harmonic balancer puller and a impact gun to break the bolt off the sensor will be behind it , I can walk you through the removal process trust me I have done everything under the son to these engines and models, I even replaced the hole wiring harness .

I doubt it’s the crankshaft position sensor . . .

The symptoms are wrong, in my opinion

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