98 Eddie 4.0 SOHC idle extremely high

[shelbygt]

I just purchased a 98 X and it recently started randomly increasing the idle speed at will. It occasionally dips low, (like when moving from reverse to drive), but at random times, in neutral or park it revs up to 1500, 2000 and 2500. In "drive" it goes to around 1100-1300. Then for no reason, it sometimes returns to normal and idles fine. It is becoming more frequent as time goes on. I don't think it is the thermostat, as it will idle up even when cold. From what I gather from searching, it most likely will be the IAC, but how can I rule out other possibilities first? Oh and there is no "check engine light"
Thanks in advance for any help..
Dave

 

[bp1506]

It is most likely the iac valve, you can clean it with a non-residue electrical contact cleaner. Also clean the maf sensor with that and it should be fine. Make sure to take the black cap on the iac off too. Then disconnect the battery cable for 10 minutes to reset the computer.

This is what i did when i had the exact same problem now its back to normal and its been a few months.

 

[shelbygt]

IAC cleaning

Well thank you to bp1506. I cleaned it out (it didn't look too dirty) and removed the neg to the battery. I drove it today and it idles perfectly.
Dave

 

[bp1506]

No problem. May start doing it after a while again but a 5 dollar can of electric contact cleaner is cheaper then an iac valve.