I had issues very similar to those described in this thread on my SRT6. Only has 38k miles on it and in excellent condition. It all started in Feb 2014 and it took me until mid-April 2014 to get it fixed. Bottom line - The RCM solder fix did the trick after much other troubleshooting! Thanks very much to tighed1 and his How to Repair Relay Control Module (RCM) - (Mystery no Start) thread.

Symptoms: Intermittently runs rough at idle, won't go faster than about 30 miles an hour. Seems like thermal issue (intermittent). Even got to the point where I would be cruising the interstate at 70 mph and it would suddenly die (all other electrical worked - engine just died). Once I pulled over and tried to restart, the rough idle and limit of 30 mph would kick in. Would eventually clear after you let it sit for a while.

Chyrsler was no help. Took it in twice and could not diagnose. Main issue was no fault codes, except the BAS/ESP light would come on once in a while. They could not duplicate.

Things done in sequence:
Chrysler did fuel induction cleaning service (no joy)
Chrysler changed out crankshaft position sensor (no joy)
I changed out the camshaft position sensor (no joy)
I changed out the fuel filter (no joy)
I resoldered the RCM. Looked like it was in great shape before I did, but reflowed the locations shown in the RCM thread and added some solder (JOY!!!)

Apologies if this is not the right place to post. I'm not a frequent poster, but the forum was such a great help that I wanted to somehow pass on my experience as well.