yes, plug is oily and carb was purchased from Parts Tree. After replacing carb, head gasket, resetting valve clearances, oil change, fresh non ethanol gas. No change.
This is another post where the OP replaced everything possible with new parts. Mower still won't run.
Back to regular programming. Check for vacuum leaks.
White smoke is water. Do you have water in the carb? Does the mower sit outside in these fall temps? Getting cooler at night depending on where you live. Any rain going on? Gas cap good?
Fouling plugs is excessive fuel. Check carb float height, air filter and carb needle. Is the fuel tank clean?