I bought a used lst 2 havin truble with it when its cold it will fire up it will run for a few minn then stall then wont start. ive had the carb off tore it down cleend it up went to fact specs on the hsn/lsn checked the head gasket its ok took the primer out of the tank any idas my savy k46 used to do this when the motor was about to die the truck is grate shape head button dint look cooked put a axal 32 spec on the savy but the mach 427 seemed to do ok i liked it good reviews is thire something I'm missin????