You would be quite surprised as to how sensitive these things are to ground issues. I had a high idle (3000 rpm constant) and I finally found out that it was because I moved my battery ground from it's original spot on the engine block to a different spot. As soon as I put it back in the original spot, my troubles were gone :shake: . I had replaced the IAC, TPS, CTS, MAP, EGR Valve, EGR Solenoid, vacuum hoses etc, etc... and was about to replace the ECU when I discovered the problem :wall: