After about 45 minutes or so of driving in hot days. My 1978308gtb starts to sputter and pop like running out of gas. I am thinking vapor lock. Car has new fuel pump,filter,fusebox,ignition coils,distributor rebuilt,plugs,wires etc.I am convinced it is vapor lock but why dont other cars do it. All emission equipment is on car and fuctional. Any ideals? water temp is 195 oil is 210 steady.