Just a thought but you may have a float sticking on one of the carbs or the floats are out of adjustment. One is possibly leaking gas from the float bowl or one may have a gasket not tight enough and may be seeping down the throat into the manifold. One carb should be not working until you put your foot part way down on the gas. Too much fuel pressure could also cause it to flood and then soot. Just a few ideas that may help. Henry
