I've been having idle issues, particularly when cold- It won't idle at all until it warms up(goes into closed loop). At startup, I have to goose it and keep the revs up, working the brake pedal with my left foot while managing the throttle with my right, almost like I am shifting a manual and working the clutch. Exhausting. Approaching a stop, I have to use my left foot on the brake, while easing back on the throttle, all the while trying not to 'rear end' the car in front!
I found a video on line of a guy resetting his IAC valve by turning on the ignition without starting the engine, unplugging the IAC, turning the ignition off, reconnecting the IAC and starting the car. I tried it and it fired and idled first time!! I thought I had solved my problem- and then it did it again!
In frustration, I thought 'my IAC has something to do with this- screw it, I'll replace the damn thing!' For $50, why not?
Bottom line- the car fires right up and idles like it should! Not only that, it seems to run better and is more responsive. It's like it has been struggling breathing with a deviated septum and has suddenly had a nose job! Boy, you can tell I've lived in Southern California too long when that analogy makes sense...

 

LOL, yea too many people spend way too much time trying to make a 20-30 year old IAC function. You can clean the carbon off them, and oil the push pin some, and reset them, and fidget with it every other week or as you discovered replace it After all they are an electric actuator so those springs and electric coils (magnetic actuation) do weaken over time. I also advise people to take the throttle body off and clean all the carbon off it, clean the linkages and the pin etc. Then put a little 3-in-1 (not wd 40) on the pin from the outside that goes from the linkages into the throttle body. Basically my rule is if its apart clean it Its amazing how long a car will last if you do that.

Also keeping the PCV valve cleaned and replaced helps reduce the junk in the intake, assuming you don't have a ton of blow-by on the engine, if you have a ton of blow-by just use a filter before the pcv line goes into the intake (or vent to atmosphere or use a oil catch can etc) until you solve the actual problem with the blow-by.