Sick slant six stalling while driving

someone already recommended checking the coil, so other things:

From experience on a 72 Duster, sounds like your condenser is failing. Will it start up just fine? After 5-10 minutes start losing power? Just barely idles and won't hardly pull itself? Let it sit for a little while and fires back up and does the same thing again? That would be on a points car.

Similar on a poor ground with an electronic ignition. Car runs well then runs poorly and stalls out. May or not restart. Ignition ground may be an issue.

Pickup on an electronic distributor; don't know why they go bad but may fail due to temperature. Doesn't necessarily run roughly, just quits like you shut off ignition. May or not restart. Pickup on distributor.

Last recommendation would be a dirty pickup in the tank. Starts pulling up debris from the bottom of the tank, clogs in the inlet. Motor stall or shutting of the car allows the debris to fall away. Start it back up and goes through the same cycle. Consider a fuel system cleaning from tank, pickup, lines, and filter.