Jeep Grand Cherokee PROBLEMS!!What else could it be???

It's a 6cylinder Jeep, and I have both a catalytic
converter and muffler...thanks to Cali emissions.  
Okay here is a rundown of what I have replaced  on
it so far....Brand new fuel pump and filter, e vap
solenoid, a 90 degree rubber elbow thing on
manifold for the e vap system, throttle position
sensor(TPS), IAC, new map sensor, new battery. I
backed out torx acres on PCM/ECU to widen the
PCM, spaced distance between PCM/ECU to the
firewall, thoroughly cleaned and zip tied wire
harness, inner black plug on PCM/ECU zip tied,
placed rag in between the PCM and coolant
reservoir tank to hold plugs in place, repaired three
stripped wires that were right right before
distributor, verified with multimeter and all fuel
injectors are good and replaced all the relays.  
Jeep still won't start, and them when it does she
runs fine for a bit and then will die while driving
down Rd and even on highway. Will cut out and
sometimes have to put in neutral and she will start
right back up and other times it will take a while for
it to start again. I have wondered if it's something
electrical because when it does cut out while going
down Rd my entire dash goes dark and flickers and
then sometimes it don't. Jeep is driving me crazy
cause I just don't know what next to do, it's proven
to be costly in figuring out what is wrong this time
around......any and all advice and suggestions on
what I could do next would be greatly appreciated
here. If you may have insight as to what the
problem with jeep really is please share!!!