Greetings,

First off, does your Service Enging Soon or Service Throttle Soon light come
on?  If so please have the codes pulled from the ECM to determine what the
computer is reading (even if the light does not remain lit the codes still
stay in the memory).

If it's a code 1216 then you most likely have a failing Fuel Solenoid
Driver.  Even if the light isn't on the FSD is still highly suspect because
the symptoms you describe are classic for it. If you're lucky and catch it
quick you can get away with just changing the FSD.  If not it will have
fried your optical sensor and you will need an entirely new fuel injection
pump.

But before you  start to worry about the expensive stuff, drain your
fuel-water seperator and change your fuel filter.  This should be the first
thing if you suspect a fuel related problem.  Next step would be to test the
lift pump under the truck to see if it's sending enough fuel under enough
pressure to your fuel injection pump.  Both are also common causes of
stalling and power loss.

If you need any more detailed information, don't hesitate to ask.

Cheers - Jonathan