Dies but will usually immediately restart.
 

94 6.5 runs fine.. running along just dies.. usually can immediately restart sometimes takes bout 10 mins. Lift pump ok. just like kill switch hit then turned back on.
any ideas?

Where is you're PMD located?? next time it dies and fails to imediatley resart pour cool water on the PMD if it fires up then that will be the issue if not the I would look at repalcing the CPS but dot not put a BWD brand in the truck as they are junk get a AC/DELCO or a NAPA brand CPS

what is PMD what is CPS.

PMD=Pump Mounted Driver this is what controls the injection pump (IP) on the engine and CPS is the Crankshaft postion Sensor this is part of the timing system on these trucks