You want to set it up so it idles steady at low throttle. Set your trim tab near the top and use the trim to kill the engine. You don't want the engine to die when you are in the air, but you might want to kill it after it lands. This can be done with the trim to completly close the throttle barrel. Your engine should have a barrel stop screw also, this is to prevent the barrel from closing off all air flow. You will have to adjust this if you want the barrel to cut off all the air flow.