Back the idle stop screw out until you can see daylight between the screw end and the throttle lever. 

For start ups, use a normally off push button to supply power to the ignition. Have an easily panicked person hold the button down. When they flee the area, the engine will shut down. Piece of cake.

 

Lynn E. Hanover

 

All I can add is clean up mess from panicked person after they flee the area.  <GGG>