high rpm while idling and unwanted acceleration

[avellino05]

I've looked everywhere so I hope someone can help me with this problem!

I have a 2003 Pontiac Sunfire, about 80,000 miles with an automatic transmission...great shape no problems. About a week ago, 20 or so minutes into my commute I was stopped at a red light and when I left off the break the car accelerated to 20mph without me doing so. As I was driving the car seemed to be getting 'pushed'. I pulled over and about 20 minutes later restarted the car and the engine revved to 3,000 RPM's and would not steady until I turned it off. The throttle body was dirty so we cleaned it up and it worked fine.

It did it again a week later but this time it was even worse. The car would only slow to 15 mph and I had to throw the car into neutral to stop the car completely before going into the intersection. After I did that I kind of got control of the car but still felt a 'push' of sorts while I had my foot steady on the gas. The car will randomly drive perfectly fine and then other times I will let off the gas and it will keep a steady speed like it's stuck or something. I don't have floor mats in the way and don't have cruise control.

Any idea what this could be or has anyone else had this same problem? Also, when we cleaned the throttle body there was a little bit of water in the air intake tube...not sure if that is in conjunction with this problem or not (i'm really not good with cars ).

 

[melsg5]

have you tried to see if the computer has any codes? have you considered replacing the throttle position sensor?

 

[avellino05]

I haven't checked the codes yet but we are in the process of taking it apart, cleaning, and checking the sensor and all. We noticed the pcv valve didn't have the rivets so it was letting in moisture which would gunk up the rest of the throttle body? would that make sense?

But this morning it did it again, same spot and time...would the temperature of my car make a difference? I find it weird that it happened 3 times at the same spots. I knew it was going to do it again because it kept going from 500-1000 and the dash and steering wheel began to vibrate a little.

 

[avellino05]

update: check engine and trac off have come on and the code error is p0507 'high idle speed'. No other codes came up. car seems to be sitting at a normal 850/1000 rpm speed but jumps to 1300 when in park and runs very rough both in park and drive. Everything is clean, there doesn't appear to be any vacuum leaks or anything with the cables. Everyone I ask suggests replacing the IAC valve and see from there if it is the sensor or entire throttle body is bad. Would this be the best bet?