I have a 1991 Pontiac Grand Prix with a 3.1L. I have changed the O2 sensor, both coolant sensors, the IAC valve, the plugs and wires 10,000 miles ago, the vacuum line harness from the throttle body, the fuel pressure regulator, the fuel filter, cleaned the throttle body, put gas in from a good gas station, and a few others things that had to be changed cause the car started running like ****. Now, she is up to it again. She has 160,000 miles on her and I put to much money in to quit now. Here is the problem.
First it started as surges at a very low rpm or at stops. The RPMs drop and go up to normal and drop, etc. It would be better in neutral. But now when i am cruising the engine starts to buck when I am on the gas and even when I am not. Also when the car sits and idles you can here from the exhaust she is not running properly. The engine light came on once for two minutes and it was a code 45 - O2 Sensor error (rich mixture indicated). You can even smell the car is running rich from the too much gas smell. The car will accelerate fine, but it will hesitate a time or two before taking off.
If anyone can give me ideas on what could be wrong I would greatly appreciate it. I am thinking it might be a sensor or something like that. Someone told me to also get my fuel injectors cleaned since my fuel filter was found clogged a year ago and everything was cleaned after that except for the injectors since dirty fuel was going through the system.
My fuel pump was tested and was found to be sending the right amount of pressure of fuel even though my fuel pump likes to make a whining noise. This problem is getting worse over the weeks and I can't figure it out and I bet it will be something stupid I forgot to think about so that's why I am asking. Thanks for your time
- Brennah
