Wow, you've thrown a lot of stuff at this thing.
Surging idles can be a nightmare to solve.
A few more things to check out.
If you have a slight vacuum leak, the ECM keeps trying to control the idle with the IAC, but it doesn't respond like it's supposed to, so the ECM keeps adjusting it back and forth.
I know this will sound crazy, but sometimes cleaning where the ground wires attach to the engine helps.
Might check the fuel pressure to see if it is staying steady.
And on rare occasion, even though you should never have to do it, I have adjusted the throttle plate stop screw a little one way or the other and that seemed to help it.
Sometimes there is just no silver bullet for idle problems.
If you unplug the IAC, does the idle stay steady?
Friday, July 3rd, 2009 AT 9:25 PM