I have been working on a 350 Grizzly and it has a problem i can not figure out. It will run for 7-10 miles and it well choke and bang cough and die. If I let it sit for a few min. it will start back up and run. I have changed the coil and spark plug, it had some carb problems got a brand new one. I have even changed the ignition control box witch was $376. Any ideas or thoughts??? I have also adjusted the valves changed the neutral safety switches.