Briggs And Stratton 19r6 Motor My Rover Wayfarer Lawnmower With Briggs & Stratton Qauntum 4hp Motor Is Over Reving And Wont Idle?

My rover wayfarer lawnmower with briggs & stratton qauntum 4hp motor is over reving and wont idle? - briggs and stratton 19r6 motor

My mower is a registered Rover with a walker 4hp Briggs & Stratton qauntum engine, the mower started as a dream, but it only works at high speed and inactivity, not completed, can someone help me with an answer to this question had also been proposed a feather in his new Governor