Won't stay running

[Caparco]

360 engine, all new, older asscesories,eg, cap - wires - plugs - fuel pump.
New carburetor.
  Stalled out one day on a drive.. tried to restart, wouldn't happen. And heard a massive backfire (thought someone shot a gun right next to me!.. lol) so may be something with timing. Thinking about towing back to the Mechanic for diagnosis. But figured I could find a easy fix with all your help.
  It cranks fine, even starts and runs, but all battery work, once I release the key, its over.like a starter cranking run.
Plenty of fuel, tested MSD coil, test fine. Cap seems straight and tight ( had previous trouble with loose cap, got a new clip from a fellow e-bodies member
And tips and advice? Appreciate the help

[Burdar]

It sounds like you're saying that when you turn the key, it cranks and starts.....but when you let off the key it dies?  Is that what you're saying?  If so, you have a problem with the "run" circuit.  While cranking in the "start" position, the coil gets full battery voltage on the brown wire and the ballast is bypassed.  When you let off the key, power transfers to the blue "run" wire and runs though the ballast.  You could have a bad ballast resistor or a faulty connection somewhere on the blue "run" wire.

The brown and blue wires come from the ignition switch.  Start by testing the blue wire at the base of the steering column where it connects to the main dash harness.  Make sure you have power on both sides of the connector when the key is in "run".  If that's good, move your way to the bulkhead connector and test that.  Then move to the ballast and coil.

[7212Mopar]

Google bad ballast resistor symptoms and start there. Inexpensive part at your local auto parts stores. Keep a spare in the car.

[DeathProofCuda]

Google bad ballast resistor symptoms and start there. Inexpensive part at your local auto parts stores. Keep a spare in the car.

I agree.  Based on your symptoms this is the most obvious thing to check first.  Check this and then report back with your findings.

[Burdar]

Instead of throwing parts at it, take the time to diagnose with a test light.  A bad ballast and a poor connection somewhere on the blue wire will cause the exact same symptoms. 

[Caparco]

Followed the blue wire from the collom look what i found at the connector! But that didn't stop power. Followed power to the bulkhead on the firewall into the engine compartment. Seems to be power there fine.. but nothing on the blue wire at the resistor... its all taped up in a bulk.. ill have to rip it out of its tape to replace?.. or see if I missed a place it went first?

[Caparco]

Why would the blue wire come out of the firewall and into the windshield wiper motor??

[Chryco Psycho]

there are 2 blue wires , one in the group of 4 to the wiper motor & the one that is the 12v feed to basically everything under the hood that has switched power , it goes tot he ballast , the voltage reg & the Alt field as well as a few other places depending on options , you may need to unwrap the harness to find the problem but that is the least likely place , usually it is at the connectors 

[Caparco]

Ok.. sorry that was my mistake I'm a little new at the multimeter tool, had it on AC.
Yes the picture above, was the problem! Ripped them out of the connector and freshly rejoined them . Started right up!
Now I'm curious how that happened in the first place, someone grabbed power for the radio off the blue wire I think, there was a (modern) crimp splice jump connector next to it.. maybe it was that.
  Thanks for all the help guys.. good work !