A properly running 3020 will need minimal choke for a cold start then no choke at all once running. So your problem is a chronic lean carb mixture.
Cause is most likely a clogged orifice in the carburetor. Disassembly and a THOROUGH cleaning of the carb internals is recommended. Also check/adjust the float level while the carb's apart.
However another other, less likely possibility is a vacuum leak between the carb and manifold, or the manifold and head.