I was riding my troy bilt 42" lawn mower when it started surging, so I changed the gas filter and blew out the ports on the carb, reinstalled everything and it still did it.
So I changed the carburator with a new one, changed the head gasket because it was leaking and put all new seals on the carb, as well as a new filter.
Also the gas is new and the hoses are good, When I started it... IT still surges, but now it makes a loud "POP" in the engine compartment and dies, or just surges real bad at high and low idle
I'm about one idea from rolling this thing off a cliff if I cant find what it might be... The gas gap seal was checked and it seems alright