I'm thinking maybe it won't idle because of the weak battery. I'd get the battery / current draw issue resolved before changing any other parts. Weak batteries will make EFI vehicles do strange things.

 

It should idle even if you pull the battery while running. The alternator powers everything while runing. The exception would be if battery is shorted and drawing current from alt. But then it would not start engine after that.

Idle is like runing - fuel, spark, and timing of those two. IAC is most likely suspect imho.

 

On lots of Chrysler vehicles, my Ram included, if the battery is excessively weak, it will not stay running. I just found this out last night with my truck. I jumped it and it started, but would not stay running unless I kept my foot on the gas, sort of like what happens if your TPS is done for. I swapped in the new battery to try and limp it home and it fired up and ran fine. Low voltage means the battery can't keep the truck running, so you have to keep the idle up so the alternator can.

On my old XJ Jeep, the battery crapped the bed and the transmission stopped shifting. The low voltage caused a condition in the computer system that just made it go "LOL WTF" and enter limp mode.

 

Went out this a.m. moved all throttle body cables by hand. Unplugged everything and plugged back in. Started turck and it idled normally.

 

Cross fingers and hope it stays. maybe the PCM just had some garbage in momory and now it is cleared. Hope it stays good now.