what causes the engine to die out

Two potential issues come to mind. First, this engine is one of several that was equipped with a TFI (Thick Film Ignition) module. The TFI module is mounted on the front of the distributor. The high heat area coupled with a weak module design caused intermittent failure - you could stall and stay down for awhile, until things cool. Second - the fuel pump could also in a similar way. Basically - find out whether you are missing spark or fuel the next time you experience the failure.