You both know, they are/were waaaaay over torqued, smashed to smithereens, leaking like my wallet.I agree with sgkent on looking for air leaks. Also verify that the gaskets between the carb and engine are installed correctly.
Pull and flush the gas tank, tank only no fuel lines. Clean it inside and out. Clean, as in hospital clean.b/s model 21r807-0090-g1 that will only run with the choke closed, cleaned carb same results only with choke closed when you go to lower speed the engine dies, replaced the carb and the same thing happens