Best way for you to diagnose at this point is to get a high quality scanner and sit down with the truck. You will need to look at rail pressure while cranking has to be so high while cranking in order for it to have a burnable spray, after it starts look at rail pressure again, actual and desired. look at balance rates
like I said before "new" injectors can be bad right out of the box, happens a lot with lb7 Injectors, where did you get them from?

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the ECM wont command the injectors to open until it sees at least 10 MPa or 1450 PSI. hence, no voltage at the injectors

-if you have a bad CP3,
-regulator,
-injector(s) ie: high return rate or stuck open,
-a collapsing/bent/pinched fuel line (rubber lines before CP3),
-cracked filter housing,
-leaking bleeder screw
-or any other leak on the suction side of the fuel pump

the engine will have a hard time starting

like turbostang7 said, a scanner that can read fuel pressure will help in determining if the ECM is not allowing it to start from low pressure or if there is another issue

also, how old is the fuel filter? batteries in good shape?