can replacing spark plugs cure loping idle. my car idles at 900 rpm then jumps to 1300-1500 rpm then back down to 900 once im at a complete stop. then it would sometimes stay at 900 then fluctuate back to 1200 back down to 900. whats the problem here? i already cleaned out my iacv which is working properly. reset the computer. still idles funny. would replacing my spark plugs do anything?

 

Dont think it could be your spark plugs. Check ignition timing? TIming belt off a tooth?

It realllllllly sounds like your IACV. Are you sure your not throwing a code when you jump the service connector? I had the problem too, and my car did not always throw a cel until I jumped the connector. How do you know if the IACV is in correct working order? Did you adjust the idle via idle screw? Check your compression? SMoke out of any parts/holes/crevices of the car? VACUME LEAKS? bent valves? Cracked sleeve? Thottle cable adjusted too tight which throws off the IACV? Air bubbles in coolant(could cause bad idle since idle is related to coolant temp), bad TPS?

These are all the things that crossed my mind when I had the same symptoms as you. Double check my list.

 

My bubbles are so bad coming out of the rad neck, that it looks like shaving cream! Any my idle is way messed up...

You should check that one for sure.