I have a 06' 5.9 2500 and on my way to work my truck started to cut out on me (engine shut off then turned on) it would come on but would hesitate. I didn't have to turn my key to make it come back on it did it by itself. Hen it would cut off my gauges would go crazy then everything was normal.. If anyone has a clue why please let me know

 

check your grounds. sounds like you have some loose ground wires somewhere.

 

Check your MPROP or known as FCA...I would replace it. I had the same issue on my 03, order the part straight from Cummins, its much cheaper than the dealership, they mark up 100%. I know on the 03 the MPROP or FCA is located behind the injection pump, held in by three screws.