Can't figure out this idle problem. Any help is appreciated
 

Hey so I've been browsing the forums for awhile trying to figure out what might be causing my strange idle problem. It is an automatic 03 Lancer ES with a 04 engine in it. The car runs good right off the start but after a period of time it will start to idle way to high. It goes its highest in park and neutral at around 2000 RPMS. In drive while stopped at a light it will idle between 1000 and 1300 RPMS which makes it so you have to hold on to the brake tight.

I bought a Idle control valve off of ebay which worked for like 2 hours then it started to idle at about 3000-4000 RPMS when in park, so I put the old one back in and it is back to how it was before. It is strange that a new one made it worse. I've tried cleaning the throttle and checked for vacuum leaks.

Another strange thing about it, and possibly important information is that when the high idle starts if you take it on the highway and go over 80-100 KM for a short period of time it will be back to a normal idle in park and drive (for a little while).

I've been searching the forums and cannot find anything matching these problems. If anyone thinks they might know what is wrong I would appreciate the help!

bumpy bump

Mines been randomly surging at idle for several months now. Truthfully, there's no single thing that causes every type of idling issue. Much like trying to diagnose a misfire, throwing parts at it is not the solution. Are you throwing any codes? How did you check for vacuum leaks? My favorite trick is blowing cigar smoke into the brake booster line.

I've checked for vacuum leaks and haven't found any. I have gotten a check engine light but it turned out to just be from cold starts and has since went away. A friend suggested the throttle position sensor

Could be a possibility. Mine started acting up one time, causing a different symptom than the one you're talking about. Easy way to check the TPS is to just unplug it. The ECU goes into a default mode, drive it around a bit and see if the issue still arises, just avoid WOT with the sensor unplugged.

I will try that tomorrow. thanks

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Tested the tps and it wasn't it. Anyone else have some ideas?