RE: 4.6 Driving me Crazy.
Take off your servo horn before setting your trim to zero with the radio on.
Set your idle gap to 1mm or the thickness of a credit card using the idle screw, the other needles are set flush.
Close the slide and reinstall the servo horn and make sure the carb closes at neutral making minor adjustments to your trim to achieve this.
Hope that helps, if it still idles high you prolly have an air leak.