Startin with basics, not trying to be a goofball. You have a little slack in cable, before throttle pulls on cable? When you release from wide open, does it go whack back closed? With carb off, does the slide close completely? Leaks can be around the base gasket, intake, carb boot, main seal(inside ignition cover), could be gummy stuff in the carb, or jetting. Air leaks and low gas flow, hung slide, all are expensive, if you don't chase it down. Idle adjustment change it?