random high idle in park

My 96 Saturn has been driven and put in park idle increases to 2000RPMs.
after about 20 seconds drops back down to normal idle and then increases
again. It was random now it is doing it regularly. But only after it has
been driven.Any ideas,

 

forgot to mention it is automatic transmission. help anyone??

 

Your Idle Air Control valve may be carboned up. Clean it, your EGR
valve, and your throttle body. Dont know what your current mileage is
but in the future post that and engine type as well.

 

defective coolant temperature sensor can also cause this.

 

tactometer climbs from 1000-3000 in 10 secs,returns to 1000 slowly, after
coming to a stop and putting transmission in park. now it feels like it
maintains 2200 rpm most of the time and like the gas pedal is feeding the
engine even when i am coming to a stop sign Mileage is 130,000 have
changed temp sensor, cleaned egr and checked idle control still no change

 

tactometer climbs from 1000-3000 in 10 secs,returns to 1000 slowly, after
coming to a stop and putting transmission in park. now it feels like it
maintains 2200 rpm most of the time and like the gas pedal is feeding the
engine even when i am coming to a stop sign Mileage is 130,000 have
changed temp sensor, cleaned egr and checked idle control still no change

 

You do not indicate the age of the vehicle. Look for a vacuum leak. The
vacuum hoses can get old and brittle, crack and suck air raising the idle.

Bob

 

1996 SL2, thank you i will check that, is wd40 the best thing for finding
vacuum leaks? you cant see or reach?
Can you tell me vacuum hose route for the egr solenoid for the liear egr?
thanks for the help!