The bowl vent has to do with the emissions only (basically when the engine is off) it wouldn't have much if any effect the acceleration of the car, though maybe if it didn't open allowing air into the fuel bowl. It sounds more like your accelerator pump shot needs adjusting and or the pump diafram needs replacement. Looking down the carb throat (air cleaner off & engine off) do you see a good pump shot (Squirt) when you open the throdle? Has the carb been rebuilt recently? If not might be a good time to freshen it up. Also check that your float level is set correctly. Good luck