Electrical or ground issue?

Hi all,

It has been a long time since I've posted but recently have been having an extremely frustrating issue. Long story long :)

Late last Summer I had a wee wirefire which was directly my fault. My ballast resistor had not been mounted on the firewall since I bought the car years before. I always looked and it and said " I should mount that puppy properly" Well I didn't and it eventually flopped over onto my choke cable casing and promptly fried a whack of the wiring right up to the bulkhead connector.

This Spring my son and I have replaced or spliced as best as we could but still have an aggravating complete power loss/shutoff that can last 1-2 seconds and then it comes back. This may happen a number of times until the temp reaches about 150F. It starts and idles fine but once you give it some juice it can completely drop but not die. Until it gets to the magic 150 F and then it runs perfectly. I have replaced the dist cap/rotor and the main wire from cap to coil. Swapped coil and ICM as I had spares. Checked/fixed grounds anywhere we thought it could be a problem.
I'm pretty good with mechanical fixes as I grew up working on cars/truck but electrical/ignition baffles me. I borrowed a multi meter but honestly not sure how to use it other than measuring voltage :)

Any thoughts /suggestions?