A couple of things to look at but the amount of run time that you are getting is really, really low as we get about 9-9:30 with our Pro guys like Kortz . Check your clutch set up. A 3 shoe clutch slips more than a 4 shoe. Run aluminum shoes unless the track is rutted or loose, they slip less than composite. Make sure your tune is indeed right i.e. you are not running a rich bottom and a lean top (or the other way around). If all of that is ok then you are going to have to take a look at your driving style and throttle application.