Soooooooo let me ask a couple things.
a) When it kills ignition, what happens? Do you have dash lights? do you hear the fuel pump prime up? Starter solenoid click? starter engage at all?
b) if you turn on the headlights and crank it, does the trucks lights dim deeply or go out altogether while trying to crank?
c) does your under hood fuse box look like this model?