My duel SU round top 3 screw runs crappy and is backfiring through the exhaust when you pull your foot off the pedal(deceleration) what does this mean, does it mean it is running rich? Any help would be appreciated. It is also running rough and seems to want to stall. I just adjusted the carbs and float.I set the floats at 9/16 they do not suck full at that point but begin when the float starts to drop, I used the FSM for the carb sync. any ideas ZDUDE1967