I recently bought this 4 wheeler and it ran fine for about a week and a half. Then it started to not want to rev up. It idles fine but sputters and falls flat when you give it gas. I cleaned the carb thinking that was the problem. After reassembly it started and ran fine for about 10 seconds then started the same thing again. Shut it off and started again and it did the same thing, ran fine for about 10 seconds then no rev. Then while it was sputtering I accidentally hit the starter button and it ran ok for another 10 seconds. Every time I bump the starter it runs great. Have you ever ran into this? Ii'm baffled.