So first off I want to thank everyone in advance and appreciate everything I have learned so far being a lurker.

Now on for the problem. I have a custom GM EFI setup using a 1227747 with a G2 chip etc. I have managed to get it to run very well so far. The EFI system is very simple on this truck and does not run a VSS or EGR. I do however have an IAC. The unit I have is a custom part with a stepper motor. It works very well but I have one issue I can figure out so far and it's hard to search.

When end you first start the engine cold the IAC acts pretty normal. But after reaching temp and running for maybe 5min or so it is still largely open. You can tell dues to the rush of air sound. The idles is decent though. Now if you restart the truck once it's hot, the IAC will almost completely close and idle is pretty much spot on. The IAC is operating drastically different. The truck will continue to run like this until you go through a cool cycle again. Really it does not effect the drive or performance at all and idle is decent in both states. But the noise and the knowledge that it's not quite right bothers the heck out of me.

So what am I missing?