Not sure if it's your problem. But the ignition coil will act like this when bad. It gets hot after sitting and breaks downI have a customers 99 king quad 300. Rebuilt the carb, replaced the intake and air box boots/seals, new air filter, new petcock and fuel pump, etc. runs great for about 15 mins and falls on its face. I’m sick of throwing parts at this thing and am lost. If you refill the fluel tank with the little gas it burned up it will start and run fine again for a bit until it falls on its face. I’m lost, any suggestions?