idle issues

[bill941]

i picked up a 99 eclipse rs for a daily driver car has 130,000 drives well but will not idle correctly no matter what I do. I am looking for more suggestions or to see if anyone has ran into the problem before.

what the car is doing is this it drives fine starts fine but when it drops to idle it seems to run rich no smoke at all the rpm jumps from 750 to about 900 no check engine light. but it acts like it has a misfire. the idle goes up and down every few seconds sometimes it will stop and just run correctly for a min or two then starts all over.


what I have done so far

checked timing (belt and water pump done 15,000 miles ago)
checked compression
cleaned throttle body
replaced plugs,wires coils
cleaned and checked egr valve
had it scaned at the dealer no problems found they also check for vac leaks they can't seem find any problems with the car but agree it doesn't idle correctly
checked for headgasket problems(was done also 15,000 miles ago)
replaced iac

I have scaned the car several times myself at work can't seem to find anything out of spec or not working correctly

any suggestions are helpfull at this point cause I am running out of ideas

car seems to have only two problems this and I can't seem the get the cap on the clutch rez for some reason.

 

[spooln4fun]

If it is jumpy on the rpm at idle it's usually your isc on the throttle body it's self. When those go out it can't help the car maintain a steady rpm so there for it kinda goes hay wire if you will going up and down.

 

[BK85]

Have you replaced the TPS (throttle position sensor)?

That's the other component that will cause the idle problem.

BK85