My 1964 F100 will die and not idle after running on the freeway or after 15 minutes of city driving in hot weather. I have a pertronix electronic ignition module with a flamethrower coil.The engine runs fine otherwise. If I let it sit for 20-30 minute it starts fine and idles fine until it gets hot again. The coil is mounted in the same place the original coil was and no part of it touches the intake manifold. I am looking for any input as to the cause. Anyone?