You might check for an air leak, usually when it runs better with the choke on, you have a lean condition. If the machine sat for a while, you may just need to clean the carb better, manually push things throught the jets and blow them out with compressed air. Also, remove the pilot screw and make sure the pilot circuit is clean. The only sensor on the carb is the throttle position sensor, and that used to match the timing curve to the throttle position.
Yours truly, sincerelly, love always, Josh aka The DirtDemon.