Before I cleaned the IAC the car would idle heavy and would hesitate for ~2 seconds on startup. It seems the idling issue has been solved, but on startup the rpms will drop to 400 or 500 for maybe half a second before returning to normal (Also there is no more hesitation while starting up--the car starts normally and then drops the rpms for a split second). Seems to be the only issue but I also haven't had a chance to go cruising just yet.

EDIT: 2000 neon ES

 

I cleaned my 2000 also and it ran rough after re-installing. I was thinking of replacing it but the part goes for $75 to $100+. I bought myself a code reader for xmas and will see what it says. I also read something about the needle plunger moving when plugged in to test if it's working or not. Good luck Richard

 

any luck yet on your fix?

 

Code reader said "no codes". One of the biggest issues on the forum because of the many possibilities to look at. So I'm back to square 1 again. Will look at motor mount alignment and IAC again when I get a chance.