I have a Toro Z Master 153, 52" / 23hp Kohler. When I engage the PTO, it stalls the engine, even at full throtle. After 2 or 3 tries, it finally will engage and then run and mow fine. After the machine has warmed up, this problem goes away. The machine only has about 90 hours in it, so i couldn't imagine the clutch going bad this soon. Has anybody had the same problem, or know what could be causing this? Thanks!