The choke richens the mixture. So, with your engine up to normal running temperature, if the RPM rises when you open the choke, then I would assume your pilot circuit (the pilot jet and air screw) is too lean.
From my experience, when my engine is at normal running temperature and sat idling, if I open the choke the engine will stall almost immediately.
Have you tried any different needles yet? How is it running at 25% to 75% throttle?
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