For anyone that cares...I had an issue whereby the CEL wouldn't come on and the IACV was ticking when I turned on the ignition on my car. Got fed up removed the ECU (pain in the butt), and metered the contacts on the potentiometer (that the screw turns). It checked out fine, showing 0 ohms in the normal position (fully counterclockwise) and 1.89 ohm at full clockwise position. I was about to give up and put it back together when I noticed that one of the wires attached to it was loose and barely hanging on to it.! Grabbed my solder iron and resoldered both wires just in case. Popped ECU back in, turned ignition on, saw my CEL on and no rhythmic ticking Took her for a short spin and immediately noticed the idle was smooth and car seems to perform better, Will take it out later on the highway and see how she performs.

 

I bet your issue was that you just had the screw turned the wrong way on the ECU.....seen it happen many times. When the screw is left in diagnostic mode the idle will be off and the IACV will constantly tick, even with just the key in the "on" postition

 

How much you wanna bet? I'm an old pro at checking my codes, had enough of those. I also took care when I turned the screw, so I was stumped when it started acting weird (there's an earlier post with the details. "Papa Grande" was the first to alert me to the issue and "Broaner" had the same problem. Basically, if that wire is loose, it causes an open-circuit, just as if the car was in diagnostic mode, and like you said the IACV valve will tick continuously and it will surge at idle & part-throttle.