ok guys my truck started acting up on me on the way home from terre haute first of all the info on the truck

07 dodge megacab dually 4x4 auto 5.9

mods

low stall billet convertor
smarty running sw 5 (back to stock now)

problem

started up an on ramp gettin back onto 70 leaving terre haute truck was in 3rd locked up and all of a sudden it was like somebody turned the key off pedal went away and the engine rattled bad....i let up and it went back to runnin fine again....pretty much ran fine all the way back to arkansas untill we stopped to eat and went to take off again and the same thing happened.....the further we went the worse it got....seems like any time you put a demand on the engine it just falls on its face no matter what gear its in

what i've done so far

first thing i done was checked the fuel pressure (seems to be fine compaired to a truck that runs fine)
second i changed the fuel filter no change
third i ran the injector return flow test (turned the truck off at 45sec allready had over 360ml of fuel)
so now i'm thinkin that its gonna be an easy fix so today i drop in a brand new set of injectors (not remans) still no change

now what?!?!?!?

seems like its runnin out of rail pressure when it cuts out if you hold it on the floor it will not accelerate but without a guage i cant tell and even if i did have a guage and it was low is it the pump is it the releif valve is it the FCA

help please

 

i would check that relief valve first, dont know how you would even check it, im not up on all that high tech common rail stuff

 

i can check it by putting on a dual feed line that i've got layin around....that will do the same thing as capping the rail.....that was what i was planning on doing, and i've got another FCA that i can swap onto the pump as well

 

updates??