Have a 75 F250 w/360 tried to start it and it would turn over but die, rebuilt the carb with same results. everytime the starter is engaged the engine will fire, when the key is let go it dies. Im figuring electrical possibly the coil or maybe the ignition module, it has electronic ignition with the module. theres not much to the motor being a 75. I know if the items are broke replacement will be required, but how to tell which one.