hey guys. I have a troy bilt rear tine tiller im borrowing from a relative. It worked perfect in the spring, but i just went to use it now, and it wont stay running. it ran for a couple minutes the first start, then i had to wait a couple hours before it would start again. Then when it did start again, it only ran for a few seconds. Air filter is good. Gas is good, and is getting to the carb. Spark plug looks ok. oil level is good. What should i try next?