Could be alot of things but kinda sounds fuel related, may have a section of rubber fuel line coming apart internally blocking fuel flow..Or a partially plugged steel line or the filter in the tank... When it acts up are you able to make it act up with the car out of gear? If so diagnoisis will be easier..When it does it does the engine just shut off or does it start to die while the throttle is open but recover with the throttle closed? If when it acts up does going to wide open throttle cause it to backfire through the carb??