Engine just dies.

1976 ford Granada 351W (wifes car) The car runs fine but lately, the car dies for no apparent reason. She waits for some time and she can get it started. Thought the carb was at fault but no. Switched from the Jacobs ignition to the factory, still happens but worse. It is like someone is turning it off. Could it be the dizzy? I need some ideas. Don't want to throw good money after bad.