Sounds like it is starved of fuel:
Hard to start: insufficient fuel with choke on
Must choke to start warm: not gettting enough fuel
Cuts out at high speed: fuel demand outruns supply.
"feathering" in a constant lean condition means that a given throttle position always supplies too much air. If you "goose" it hard, it dies right?
Check:
fuel filter, fuel line to carb. before removing snd cleaning the carb.
Mark
August 2008