Bought a Lazer CT 52" with a Vanguard 18hp new May of 2005. I mowed my yard +/- 6 times this year with no problems. Now the engine is sputtering, and has no power. Everytime I engage the deck the engine dies. Black smoke will billow out at startup. I had this same problem 2 times in 2005, but it seemed to work it self out. Any ideas where to start?