I have a craftsman DLT 3000 riding mower . more importantly leaf picker upper. Anyway the tractor ran fine until this past weekend. It was very hard starting even with a jump. I adjusted the valves as per B&S instructions. It ran fine for an entire weekend .I went out today and the tractor starts ,runs for about 30-45 seconds then dies. Again its a B&S 18.5 intek .Any ideas ?