Tractor Repair: 1983 ford 4500, head gasket, full stream

Question
what would make my tractor want to die when it starts getting warm?(i have to pull the choke to try to keep it running)but it eventually dies and wont run until it completely cools down)i have rebuilt my carb and i need to put a head gasket on it.ive got a new battery,plugs,wiresand oilchange

Answer
  It could be either fuel or ignition related, but if pulling the choke out helps for awhile, then it is probably starving for fuel.  Check the flow of fuel from the tank.  It has to run full stream out of the fuel line, a small dribble is not enough to supply the engine under load.  If necessary, remove the shut-off valve from the tank and clean it out to get full flow.  A bad ignition coil or condenser could cause it also, but it sounds like a fuel problem because you said you have to pull the choke to keep it running.