I bought a 2006 trx450er a while back and and everything was running great. It had not been sitting and it has had no mechanical work done other than oil changes. Then while I was on it riding it started cutting out and backfire Above half throttle. It idols perfect and it runs perfect up to half throttle. I've completely rebuilt the carb, and replaced the jets with OEM jets. I replaced the spark plug, the air filter, and the accelerator pump. I've checked everything I know to check. Can someone please give me some helpful advise?