I have a 2005 Chrysler 300C.

poss electronic throttle control.scan codes and post so we can adv

Solution may be to have it test driven , with scanner reading 'live' data , while duplicating symptoms you describe. Next time it happens , don't pull over and stop (if traffic permits) , just put in neutral and shut it off(NOT TO THE LOCK POSITION!!!) and restart it , put back in drive and see if problem goes away , IF it does , then probably a wiring or connection issue. Would still need testing to confirm proper diagnosis.