Car died during driving

I had somewhat the same issue with my 72 Demon 340 Auto. It would do what you described every once in awhile. I mean I would go 8-9 months with no issues then it would happed. I can't say for sure but I think my neutral safety switch acting up, but It made sense to me. I was told that next time it happened to move the shifter back and forth a few times. Bingo it started! I haven't had the issue since I replaced the switch and adjusted the linkage (Knock on wood). Hope this helps.