I don't know if these cars have carbs that sit on a sandwiched rubber gasket like the older Audis used, but if so, the rubber could be split. Start the car and let it warm up, (if you can) then grab the carb and gently rock it in all direction whilst listening to the note of the engine. If the engine stalls, changes rpm or other strange things, then the chances are that the gasket is split and you need a new one.