318 stalling while driving

I had an ECU that would fail this way. Get hot and quit. I used the same process you did, put it in neutral and restart. The ECU box case needs grounded well too and sometimes poor grounding can causes issues.

Starting and not staying running might be a different issue like ballast resistor, fuel, or other electrical issue. Every old car my dad and I messed with has needed a new ignition switch.