Normally, I can find solutions here without posting, but I can't seem to find an answer now.

My 99 Rodeo normally idles below 1000. Over a period of 2 days this works its way up to 2500 - 3000.

I have replaced the TPS with no change. If I disconnect the battery for 15 seconds, it works fine for a day or so then the idle problem works its way back.

Any suggestions welcome and thanks in advance.

jafo2k
Nova Scotia Canada

 

first check and clean your (iac idle air controler) thats what controls idle speed mine keeps geting gumed up for some reason but mine just might have a gremlin living in it

 

im not sure on yours but it should be up on the fender

 

Idle speed is controlled by a electic idle speed controller, mounted on the air intake /trottle valve body. Basically it's a electic motor which extends or retracts an air plunger as needed in the air bypass around the closed throttle valve to regulate idle speed.
These things are known to fail or operate eratically!