my 2007 ram 1500 5.7 ran fine yesterday,then this morning, I started it, and the engine would rev to 3000rpm's, then all the way back down, and then sometimes die. WTF? I unhooked the battery for awhile, tried it again, and made no difference. And this happens, in park, or in gear.

 

Welcome to the site. Any check engine lights? First time it ever did this? Checked for vacuum leaks?

 

=could it be the IAC, mine is bad on my dakota 5.2 but i dont know if its the same with the hemi

 

You might try cleaning the TB. Its a simple task. Fixed mine when it did that.

 

IAC is part of the throttle body and most likely the culprit.