More likely, you've got a vacuum leak somewhere. Does the engine surge , stall, or just quit running when the idle speed is lowered? Is there a hole in the throttle plate? Sometimes it's necessary to assure that the edge of the throttle plate contacts the bore above the port with the mixture needle in it, and doesn't expose the "part throttle'" port that isn't adjustable. Also check to be sure the ignition timing isn't too late- - - -that will make it necessary to raise the idle speed to get a little centrifugal advance dialed in. Try closing the choke plate a little to see if you can drop the idle speed without stalling when the mixture is richened up a bit.
Jerry
