SOLVED

Hi folks, I figured I'd report back on my troubles and close this thread. Advanced Diesel had my truck in the shop for 3 weeks trying to figure out what was going on. Eventually they narrowed it down to the optical sensor at the top of the IP. They put a new one in and the engine stalling disappeared.

That was two months ago. I drove it several times a day since, around town and to the mountain and in all kinds of weather. The engine has not stalled once, so I think it's safe to say that the optical sensor was the source of the problem.

Kudos to Advanced Diesel for a job well done, and a big thanks to Robyn for recommending them! Oh they also noticed 2 transfer case mounting bolts were missing and replaced them.