[Oldsguy]

Mark, it may not be fuel delivery problem, it may be a warped baseplate and/or ripped baseplate gasket. With that condition you may draw excessive air intermittently for no apparent reason. Worn throttle bushings can do that too. If your car is idleing or running at part throttle happily and all of a sudden it leans out it can stumble and starve that way and not be a fuel delivery problem (except for lack of negative pressure in the venturi, hence no fuel). I might be way off base but just trying to help. Sorry for the delay in answering but haven't been here lately what with the server problems and such. Good luck.