I have a Huslter 19/52 with the kawasaki 19HP engine. I got it toward the end of last year and have mowed 8 times or so this year. Only about 15-20 hours on the engine. Today while mowing the engine start to surge and act like its cutting out and then surge again, continuously repeating the cycle. I shut it off for a few hours and let it cool down. When I started it back up I had the same problem. Any thoughts on what may be wrong?