#1fuel tank is not breathing. make sure tank vent not pluged
#2 some tanks have a second line that allows a slight positive pressure to fuel circuit.
#3 check bottom carb. vent holes if blocked the fuel pump can't deliver enough fuel under load.( low RPM/ no power under load)
#4 check carb. diaphragm for pin hole(S) and proper seal around edges
#5 install carb overhaul kit.
note: craftsman has parts and inst. REPLACE CLUNK AND FUEL LINE INSIDE FUEL TANK. CLEAN TANK
Darcus Lieter Arkansas USA, September 2008