2003 Ford Expedition 5.4 L Trition Electrical?

Hello all,
I have 2003 Ford Expedition that has been giving me a hard time. The
vehicle will randomly die while I am driving it. The lights on the dash go nuts,
but everything else is dead. I have replaced the battery, the alternator, the
Powertrain Control Module (PCM), a vacuum hose thing in the back that was
close to the idle air control valve, I have also replaced the idle air control
valve, and after replaces the multiple relays I  have just put in a new fuse
box inside the cabin. I have checked to make sure the wire that goes from
the infusible wire clip, but over an AC metal pipe was not messed up. I am at
a loss here. My wires all seem to be in good shape. The vehicle seems to
run ok at an idle but as soon as I touch the brakes to go into reverse the
vehicle dies. If I can get it into reverse without dying, the vehicle dies if the
air turns on. or if I try and roll a window down. I think it is something electrical
but I am not sure. Oh, sorry for the scattered thoughts here but I also put in a
new windshield before replacing the fuse box because I had read about a
leak and it getting into the fuse box.