2012 Chrysler T&C Limited Shuts off instantly while driving at interstate speed

Our family was returning from summer visits to family  in SC last week on I-
95N and Route 17N.  My wife was driving and during a slight uphill
accelerated to maintain road speed and the van shut off instantly with a
slight click or clunk (as if an electrical-mechanical device disengaged...)
losing both power steering and braking. She wrestled the van to the side of
the road where we immediately tried to re-start.  The dash trouble lights
cycled and all turned off except for the Electronic Throttle Control (ETC) and
Check Engine Light (CEL).  The vehicle had all electrical power and would
turn over but not start, all while the ETC and CEL and sometimes the
Electronic Stability Control (ESC) light remained light (no blinking...) started
to troubleshoot and checked the fuses in the TIPM, (all good), then I checked
the cables from the battery and the TIPM for wear and tear or loose
connections and tried to re-start. Car turned over and would not start.

Then surprisingly, after about 40-50 minutes the car started and we drove 15
miles down the road and it shut off again.  After 40-50 minutes, it started
again and we drove very conservatively home about 80 miles.  We took to
our Mechanic and without a diagnostic code, suggested we drive until it
failed.  We did so, again driving on interstate, at speed and it failed.  This
time, we had it towed to our Mechanic and left with them.  They could not
repeat the issue (as it appears, you have to be driving at interstate speeds
and things have to heat up before it will fail...).

So there you have it, any suggestions very welcomed!

As a note, we are replacing the fuel pump at a little over $800 parts and
labor, all after explaining above to local Mechanic and Chrylser Service GM
and one of his Mechanics, who all stated most likely problem.

I am simply trying to avoid multiple $800 repairs chasing this down and
hoping someone can help.  Thanks.