Oldsmobile/Buick Repair: 2000Buick Regal Acceleration problem, coolant temperature sensor, throttle position sensor

Question
I have a 2000 Buick Regal GS. I noticed 1 day that when the car is idling, the RPM goes up and down, suddenly. While driving 1 day, the car felt like it couldnt accelerate at all. Had to gun it, just to speed up, versus the normal acceleration. I switched to Sunoco 94 Octane, and the problem seems to go away, but it has me concerned. I have a check engine light, But once i took it to Tuffy's the Mechanic, mentioned that there was nothing wrong. A little help would be appreciated.

Answer
Hello Ron,
One thing I always like to do is check the fuel pressure. It must be within specs.
Then, there are many sensors feeding the ecm, which crunches the numbers, and then decides how mych air/fuel to send, as well as where to time the engine.
It also operates the egr valve, and the vapor purge valve.
Just about any of the sensors giving a strange reading could cause the speed up, etc.

If the fuel pressure is up to spec, cleaning the egr valve is a cheap, easy task, that should actually be done occasionally.

Mass airflow sensor being dirty, or the coolant temperature sensor out of spec, or even a lazy oxygen sensor could also cause that.

Read these links.


http://www.fordscorpio.co.uk/cleanmaf.htm

http://www.chevytalk.org/threads/showthreaded.php?Cat=0&Number=1366279

http://www.misterfixit.com/egrvalve.htm

The other thing that can make the throttle seem unresponsive is the throttle position sensor.

Van