Got my honda civic 97 LXi, I have a check engine light on, and unstable RPM on idle, it jumps back and forth on 1400-1600 rpm, I tried to unplug the IACV but still the same, though in running the car even on a highway there are no problems, just when the car is on idle, do I need to replace my IACV, is there anyway I can check if it is broken?