Tractor runs for 20 to 30 minutes and then dies, surges, dies. Let it sit for 1 hour and it will run for 30 minutes or so and start dying. 8 second cycle of rpm going down to almost idle, surge, idle, surge. Cleaned tank and fuel lines. No help. Changed fuel. Replaced fuel lines, fuel filter, fuel cutoff valve. The problem continues. Local dealer says he does not know what further to do. Do I turn this tractor into yard art? Very expensive yard art. Help!