i've dealt with many pump issues on the road to 700hp with my 2002, from starving the pump causing it to cease to having too much backpressure from the the OEM cross tubes causing it to cease. the best sure fire way to see if it's your pump or your lift pump is to loosen the return line off your VP pump. crank the truck over and if nothing comes out then chances are it's your lift pump. to tell for sure remove the banjo bolt going into your VP pump...you should only have to turn the key to the ACC position since this is the time the lift pump primes the injection pump. so if diesel does or doesn't come out of that line...well you should have your answer right there.
if you do get diesel out of your inlet and return line then i'd guess you vapor locked your injection pump. very common problem, just take a 3/4" wrench and crack loose a few fuel lines going to your head and bleed them out. but easiest way to check for any fuel is the inlet and outlet banjo bolts on the side of your injection pump. very easy to access, very easy problem to diagnose. check these yourself before you start spending any money on a mechanic/parts.