Could be the idle air control.

Helpful video here: Video

I have to give a mention to this Guy on Youtube, "Splelunkerd" that his 2nd Gen Ram videos are the best I've seen. He gives really clear instructions, lots of common sense style repair tips, and is smart as hell; worth subcribing or favoriting in your browser.

This Fellow takes the whole thing apart, but I just pulled mine out from the back, cleaned it with brake cleaner and was good as new.

Usually, Rhino if it's the IAC the idle will wander when it's cold. Hopefully, this is what your issue is (free fix )