1973 Plymouth Scamp accelerating/braking issues, please help
It still sounds like either a heat-related ignition issue wherein an ignition component failing when it gets hot, or a fuel contamination issuetrash in the fuel tank gets sucked against the fuel pickup screen as the engine runs, eventually blocking it off. Stop the engine, suction goes away, trash floats down off the fuel pickup screen. Eventually enough trash drifts away from the screen that the engine will start and run again.
Unless it's a failing connector at the bulkhead disconnect -- have you checked/cleaned? -- it's probably not an electrical issue because you've replaced all the suspect components (coil, ICM, and the pickup in the distributor would've been swapped when you replaced the distributor as a whole).
The next time the engine stops and won't restart, remove the air cleaner lid and operate the throttle by hand as you peer down the carburetor. If you see a shot/squirt of fuel emitted from the sidewall of the carburetor throat towards the centre of the carburetor throat, then you're not lacking for fuel supply and my clogged-screen guess is probably wrong. But if you see no such shot/squirt, you've got fuel supply problems, probably as described above. If you
do have fuel, the next test is to check for spark by removing the ignition coil cable from the centre tower of the distributor cap and holding it (by the wire insulation) so its metal end is about 3/8" away from the cylinder head casting while someone else turns the key to the "Start" position for you. If you see sparks flying from the end of the coil wire to the cylinder head, you've got spark. If not...time for more electrical diagnosis.
So why did it run so well after replacing the distributor? Perhaps because enough time went by while you were doing so for the crud to float off the fuel pickup screen.
possibly a transmission problem?
No.
I replaced..
Carb - Holley 1920
Replaced with what? If a "remanufactured" carburetor, you've probably bought yourself more problems, not fewer.
Ignition Coil (Disconnected Resistor - is it necessary to have it grounded?)
This doesn't make sense as written. Why did you disconnect the resistor? And what is it you think should be grounded?
Your car doesn't have points.
BTDC.