Just bought my timemaster 30 in June and it has already started surging? It starts fine and sounds normal until front lawn has been mowed. When the blades are disengaged, that's when it starts surging. I'll usually refuel for the backyard and it starts right up but still surging until the blades are engaged, then the engine runs evenly until the blades are again disengaged. Also, at the point it surges, there is a strong fuel smell like it's running rich. The mower is three months old, any idea why I would be having problems already? I have 1/4 acre yard, the front is about 1/3 the size of the back yard but a steep grade, don't know if that could be a problem?