318 stalling while driving

Nearly every day for a week I start my ‘76 Dart w/318 2BBL and drive about 6 miles. While cruising along at 55 mph it will die. I slap it in neutral fire it back up and continue on my way without any issues the rest of the day. Yesterday it wouldn’t restart, pulled off the road, I could get it to start but wouldn’t stay running. Fuel line is clean
Any ideas where to start?

having the same issues with a big block and an msd ignition , complete rewire , new ign. switch, new coil, new relays, new starter, and wiring to it , new battery, wondering about the msd 6al , but it fires when tested-----------???
ANY AND ALL SUGESTIONS APPRECIATED !!!!!!!!!!