Kohler CH20S-64660 on a Walker mower. Runs great at full throttle but refuses to idle. Done to date: 1) Disassembled and cleaned carb 2) Replaced fuel filter 3) Cleaned screen on intake tube in fuel tank 4) Adjusted float to spec 5) Adjusted idle speed screw 6) Check all hoses and lines for condition Engine seems to be flooding out at idle, hard re-start. Fuel is also getting into crankcase. Fuel pump appears to be working just fine but fuel filter refuses to fill completely. Could the pump be working sufficiently at full speed but not at idle? Could the selenoid need replacing? I'm at wits end and any suggestions would be much appreciated.