If you aren't sure it is over fueling, I'd check for running lean first by doing what Paul suggested, check for a vacuum leak at the squirrel condomns and also check the intake rubbers that hold the carbs to see if they aren't cracked. Too much air at idle will cause this but not really affect your top end.
If the float is stuck, you should see fuel coming out of a carb vent or even fill up your crankcase.
