Did you check the air filter? It can make a fine rodent nest as can the exhaust pipes. The hidden filter between the carbs? Stabil can really clog a tiny filter like that. That said the most likely culprit is one of the circuits in the carbs is gummed up and that just taes persistence and lots of cleaner spray.

A positive attitude may not solve all your problems, but it will annoy enough people to make it worth the effort. Herm Albright (1876 - 1944)