an addition to my last, ky car was idleing from 1000 rpm to 2000rpm back and forth. and it was the problem i listed before. easy fix. it took 30 min. part is kind of pricy though. the way you can check it is to unplug the sensor that goes into your iacv and the car should idle the same. when you plug it back in if noting changes then its bad. the part was 170.00 at advance auto.