idle air control valve troubleshooting

i keep having a code for a bad idle air control valve and i have had it replaced twice on my 95 k1500 with a 4.3 v6. it runs like crap until it is warmed up all the way, then it runs good until you kill the motor and let it cool off at all. first thing i need to know is how to troubleshoot these deals, there are 4 wires in the connector that is plugged into the valve and i have no idea which of them are hot and whatnot. if anyone here knows, that would be a great deal of help to me

also, do aftermarket idle air control valves have a tendency to be junk? i had the original valve replaced at a shop and it worked for a week or so and went bad on me again. i also just put in a duralast brand one today and it didnt work from the get-go. i might have to pony up 60 bucks for a dealer supplied original manufacturer one. any ideas?

If you are looking for assistance using the term running like CRAP is not very helpfull...Just exactly what is the problem? any DTC'S?...ETC...

I'd check the wiring harness for breaks and/or a bad ground wire. Any trouble code clues can help, too.

I also know that you can adjust the extended length only on a NEW IAC valve. Trying to adjust a used valve by pressing it in with your thumb can break the innards. Thinking along this line, I might hazard to guess that others have replaced theirs, adjusted it, found out it wasn't the problem, and took it back. It gets reboxed and resold to you. Would you get THAT many used ones? Doubt it, but then it's kind of rare they actually fail. Most just need cleaning. Replacements usually come from some numbnut who wants to push in the little springy-looking tip. Hope this helps!