...My first thoughts:
Fuel Pump, Clogged Fuel Filter, Clogged Main Jet(s).
Fuel Tank NOT Vented.
* Vapor Lock, Fuel Line to close to Header, or Carb Needs Heat Insulator.
Coil Bad, Points Closing-up-Burned (if the dist. is using points) Bad Condenser/Capacitor. COIL wired in REVERSED Polarity.
Spark Plug Wire(s), Coils High Tension wire, Shorting to Ground (May cause Backfiring).
Bad/Burned Ignition Switch...Bad Ground to All Ignition points.
Headlight Motor Wired 'Incorrectly' into the Ignition Circuit.
Bad/Failing Alternator/Voltage Regulator
There Are Tests for all of these conditions.
Very Glad You did not get Stalled In the Middle of the Freeway!!
Good Luck with it.
MJ
Last....If the Rad. Fans were to be wired, by Mistake and Incorrectly, into the Ignition circuit, everytime a Fan came ON, the Ignition would shut down.