My sled has been fouling plugs since new. I've had it to the dealer several times for this issue and they cannot seem to figure it out. Now today it has "det" code and reduced power. I use 91 octane fuel and have tried other plugs equivelant to bpr9es to no avail. The dealer adjusted the tps the last time and it seemed to be ok for a little bit. Any help would be appreiciated