I don't think the boost referenced PV's are an issue with a blow through setup. Maybe if the carb is too small, but it would have to be small enough that you start to drop boost under the carb and pull enough vacuum to close the PV's. Aside from that, how are you having trouble setting fuel pressure? Did you boost reference the pressure regulator? How about your spark plugs? Are they cool enough that it isn't detonating and loosing control of the combustion process? Is your coil up to the task of firing a boosted engine? It's possible that it loses its spark and then there's no exhaust to create boost. I'm just throwing out suggestions.