feets I don't know if your carb has a black plastic cap, cover or screw on the left top side of the carb (white arrows area) that will have that vent passage when removed? That's what causes symptoms as you describe when it gets even a little blocked. If it does cleaning it with some carb cleaner and air pressure and best with an ultrasonic parts cleaner should fix it............ Sure sounds like a float bowl venting issue to me as the float bowl holds about 1-2 minutes of running time fuel.......or less.