===========================I don't know the technical reasons.... But I did try cleaning my original iac valve, but it didn't help. I feel the original one is broke/dead.
The cars at junkyard are usually there because of a wreck so some parts are perfectly fine. But as always your mileage may vary.
Did you take it completely apart to clean it? Dissasemble it completely, twist out the plunger and pull out the spring, then clean it good. When reassembling, twist the plunger all the way back in. You'll likely save yourself a bunch of cash. Easy job, they get gummed up bad over time.currently I am just suspecting that is the cause of my problem my rpms have been jumping up and down irregularly and I already did a good cleaning of the throttle body and the idle air control even after the cleaning it seems a little better but when the car is in park they still jump up to 1000 or 2000 rpm.then when I put the car in drive they drop back down to 600 no check engine lights or codes are present.
==================before anyone asks I'm not getting any codes I did clean the idle air control really good and throttle body about a month ago the RPMs seem to be ok now other than the occasional glitch however whenever the car is in park it's still constantly shaking very weird almost like someone is tapping on the gas pedal a little bit but the RPM stay at 650 why would that be? would that be my plenum I'm waiting on to replace or something else