Hey guys! I've got a 10-year-old Grasshopper 718K that has recently developed a problem. After mowing 30 minutes, or so, the engine begins to stutter and occasionally backfire. I suspected water in fuel, but here's the head-scratcher...When I turn off the PTO, the engine runs perfect. If it was a fuel problem, wouldn't the engine still stutter when the PTO is dis-engaged? Now, I'm wondering if the problem isn't electrical... Any thoughts from the Gurus? Thanks in advance for any replies.