Gentlemen, your assistance please. My 4.6HSE has an intermittent starting problem. Only when warm. It fails to start instantly ,as usual, and continued cranking does no good. But if I hold the throttle fully open and keep cranking ,it eventually fires for a moment. Repeated attempts (between 3 and 6) will ultimately result in the motor bursting into life as if nothing happened, although all this is accompanied by large clouds of black smoke. Any ideas please?