Engine/Transmission (1998.5 - 2002) why is this happening

[gottorq33]

ok here it is just got vp44 replaced truck runs great sometimes. Sometimes when I start truck fuel pressure is 20 idle and 15 cruise and 10 WOT less smoke better throttle response other times when I start truck it makes 18 psi idle I can pull it to about 11 or 10 psi when I accelerate easy like off the line maybe 1/4 pedal and 8 WOT is one of the pumps going weak or bad vp44 was replaced not due to low pressure and pressure test made more then enough volume of diesel when dealer tested it before replacing vp and sometimes like I said before truck is hard starting either cold or hot past couple of days it was fine yesterday I parked on hill facing up and it had hard time starting this is driving me nuts