Fuel Pump Issues?

That problem is in the carb not the fuel pump. The bubble in the fuel filter is normal. You can relocate the fuel to a vertical position behind the altenater and get the bubble out or buy a metal filter so you can't see the bubble. LOL
GM quadrojet carbs had the same symptom. Their venturi bleed tubes would drop out from where they were sataked into the casting. Slow throttle open was fine but quick throttle open caused hesitation and backfire. Hope this helps.