Had that happen with my Chevy class C about 25000 miles ago. Happened twice within 5 miles of each other while travelling downhill after pulling a grade and hasn't happened since. No codes and just shut off. After sitting for 30 minutes started up and never happened again. Had a lot of talks with mechanics and never found the cause. The only thing that I could think of was that it was a hot day and had driven about 600 miles already. The engine compartment was very hot so I wondered if it could have been vapor lock as I had that happen a couple of times in the 70's with a truck I had.