Yesterday I was stuck in traffic on my way to the airport and while at idle, the truck's rpm would go from approx 600 to 1500/2000 in pulses a few times. Its happened for about 20 minutes off and off and then stopped. When I go back from my trip later in the day on the way out of the parking garage (engine cold), while in neutral the truck stalled and did it a few times. Nothing this am. Any ideas what this could be? Its a 2004 Ram with Hemi. 65k miles.

 

most likely a classic dirty throttle body issue. read through this thread, it'll be all you need.

 

I agre, sounds like a t/b issue.