High idle won't drop

[jimbo231]

I have a 1998 explorer xlt. When its cold and I start it it revs at about 1500rpm but takes almost 5 min to only drop to 1100. Does anyone know what causes this?

 

[BrooklynBay]

Welcome to this forum! Where do you live? Do you live in a cold climate? It could rev a lot until it warms up.

 

[alohamonte]

sounds like what happened to mine when the thermostat failed

i'd say run the truck with the radiator cap off to check if the coolant is circulating. if it's stuck in warm-up mode, the idle won't drop.

 

[BIGHVM]

Its the Iac valve, I believe- needs cleaning, read about it by doing a search. It is a common fault poor idling, mine did the same would start and idle around 1.5k!
After cleaning the Iac- fine now idles normal.
Let us know when you have done it and post a Pint to the UK- Lol!