I would dissconect the linkage between each carb and adjust the carb idle screws untill flow is same with both carbs, need to check with flow meter, if you don't have one you can use a piece of 3/4 inch heater hose hold one end to front of each carb and other to your ear you should be able to get them close. if you you had a leak at the manifold it would run very lean and not pull air though the carbs