I have a 2000 Ford expedition and at times the engine revs up and down when In park.
Hi There, It sounds like you may have a dirty or faulty idle control valve which may be causing the engine RPM to fluctuate. This valve monitors the air flow into the engine and sends a signal to the computer based upon measurements taken. The computer uses this information to control the fueling of the motor depending on engine load and certain factors. When this is not working properly, this may cause your engine to idle erratically or stall in some cases. I would suggest having a professional from YourMechanic come to your location to diagnose and inspect your vehicle.
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