080202-2324-01 Air vane governor setup.
On these engines the fuel tanks tends to rust. This rust can enter the carburetor main tower and clog the metering passages causing lean burn that sounds like you're experiencing. It would take someone with the experience of removing and replacing the steel balls to clean out these passages. Since most don't have this knowledge it is best just to replace the carburetor, add the filter screen below, and if need the fuel tank.
This problem of clogging could have been prevented if only the setup had the 691213 filter screen in place with but according to the IPL this engine wasn't setup with the screen installed. This still doesn't resolved the problem of the fuel tanks rusting.
