My 2001 Ram 1500 (4WD) had a dead battery yesterday. I charged the battery and now it will start right away but dies when I let up on the gas. I thought it might be the IAC but I am worried about why the battery was dead to begin with. Any ideas?

 

Battery's too weak to keep it running. Replace it and you're golden.

 

+1, and after you replace the battery the PCM will need a little time to relearn the IAC settings.

 

your battery is probably still low on voltage. check it with a voltage meter and load test.

low voltage screws up the idle signal.