Grizzly is right. If you want to get a GM hermaphrodite system to run you would probably have better luck on an LS forum, just don't tell em its a hemi. It is probably a computery issue not an issue with the actual chrysler stuff you are using.
The Gm transmission is on its own system and has zero effect on the engine management. I would have gone the GM trans route if I did not find a 518, the 518 at least where I am is very hard to find and I'm regretting it at the moment as a high stall lock up torque converter at the moment is not available.I have been waiting 2 months and they tell me they can't get parts. Too many people freak out about miss-matching brands.
I see the engine has megasquirt if its from efi source. The hot idle should be set by the idle screw on the throttle body. The IAC motor usually controls cold idle and a boost for the AC compressor.
You need a laptop and the tuner studio software and see whats going on with it. I only know the holley efi. It should work the same. If you could data log the stall you would be able to see what happened, the IAC should stop that from happening if it was set up right. I would not throw parts at it without knowing whats wrong.
When its hot unplugg the IAC motor and see where it idles, that will tell you how much its using it when hot, should be 2-5%. If it drops alot try raising it to where you want it and plug the IAC back in. Its commanded an idle rpm so it will close the IAC and not run any faster. Since you don't have the software that may not work as the tps will need reset.
