Had very similar thing happen on my 2001 Safari Zanzibar. Just shut off going down road. Had unit towed to Cat dealer, Thanksgiving eve. As I started to think this over the check engine light was not on. That was the answer. The fuse for the ECM quite making contact. Pulled out fuse and it was not blown but holder showed extreme heat, melted plastic. It seems China has been making the fuses from thinner material. I found a old made in USA fuse and measured the thickness. The USA lugs are .015 thousands thicker. Could not find any 20 amp ATO fuse so used breaker with copper lugs .020 thicker. End of problem.