Starts up good but will die unless I feather the gas a few times to keep it going. After warm up runs good. This is a new rebuilt carb I bought from National Carburetor Co. I sent it back to them for this problem and they supposedly fixed it but still same problem. Things I have done to solve problem. New fuel filter in carb, New fuel pump. Good fuel flow from fuel tank gas line to fuel pump. Tank is vented properly. Does anyone know why this is happening? Any help is appreciated.