Owned this car 9 years and for the last say 5 years when the temp gets below freezing the car idles at about 1200-1500 rpm’s. When it has been driven and then put into park, the rpm’s will jump to 2000 and climb staedilt to about 3000. When it idles high the car also is harder to stop and on a flat road will accelerate itself, changing gears until it gets to about 25-30. Love this car and it only has 108,000 miles on it. Hope someone can tell me what is wrong.
Is the check engine light on?
One possibility is that you have a sticky idle air control (IAC) valve. This probably sits directly on top of the throttle body and the next time it happens you could try giving it a whack with the end of a screwdriver to see if that changes anything. These can be pulled and cleaned. (The IAC controls the amount of air going into the intake at idle. If it sticks open some it will cause a high idle).
I agree with cigroller that the first thing to check is the IAC.
Cleaning it is really cheap, and replacing it is not hugely expensive.
Certainly replacing the IAC is far cheaper than the consequences of an accident resulting from difficulty in stopping the car.
While I applaud the OP for asking the question, I also have to say that I am appalled that he/she has been driving a car in this condition for 5 years!
VDCdriver perhaps I need to clarify. What i meant was that when in park after being driven the car’s RPM’s go up to 2000-3000. When driving they are between 1000-1500 and when you take your foot off the brake the car will go forward w/o the gas being pressed. As for the length of time well…goes away when the weather is above freezing and if the car has been driven park and then driven again when still warm it doesn’t always rev. Out of site out of mind i’m afraid. I have never had difficulty stopping the car but can feel the car wanting to go when it revs. I thought perhaps it was a vacum leak. Hope that makes things clearer.
Vacuum leaks would be another thing you could check - in essence, it would be the same thing as an IAC that gets stuck partly open - too much air. Its just that an IAC would more likely be affected by the cold.
If you want to check for vacuum leaks you can a) use a small piece of hose as a stethoscope - one end in ear, and the other fishing around all vacuum lines and connections (there is a schematic diagram on the underside of your hood). Listen for a hiss; or b) hook up a piece of hose to a propane torch and - without lighting - feed propane around vacuum connections. Wait for change in engine idle.
Thanks. I will look into both. I appreciate you taking the time to respond!