I have a 1999 Ford Expedition (5.4) and it is hard to start not all the time but I would say one in 10 times. When it does it I tune off the key and listen for the fuel pump to whine sometimes I cant here it and it will not start. I tune the key off and on and try to hear the pump sometimes I can other times I cant. The truck has 92,000 miles on it. If it would just fail it would be easy. Just don't want to strand my wife.
I would replace the fuel pump relay to start. If the relay doesn't close, no power to the fuel pump, meaning no start. A relay can start to go bad without completely failing at first if the contacts inside start to wear out.