I would either say that the float isn't sealing off allowing too much gas to enter the engine, or some of the kaws have a vent tube coming off the carb, that the mud dabbers like to build nest in, and if the carb vent can't breath can cause the problems that you describe.
Another scenerio could be a plugged air bleed, in the carb, but that may be a little above you understand, because I don't know your mechanical abilities.
Air gets mixed with the fuel as it passes through the jets to help atomize the fuel. If the air doesn't mix can cause a rich run condition.