Small Engines (Lawn Mowers, etc.): Over rev lawn mower

Question
Hi my lawn mower recently has started to over rev, and wont shut off to the point it starts to back fire, and still wont stop, the controls do nothing. after all this it might cut out or fuel is turned off and it winds down. After when mowing again the revs stay very low, and all of a sudden it starts to over rev again and same back fires and is uncontrollable..
my mower is a Victa mustang 2 stroke.

Answer
Has the carburetor been cleaned?  I'd start by removing, dis-assembling and cleaning the carburetor with compressed air from an air compressor.  Blow compressed air through all the carb orifices.  I would also check all the carburetor linkages and make sure they are clean, free of grease, dirt/debris, and move easy without any binding.

Let me know if cleaning the carb helps.

Eric