I know that this is not the place to ask about car problems, but I couldn't get a good response from the Lincoln Forum and in the past, some brilliant people on this forum have saved me thousands. ...
Something quick and easy to check. Next time the engine will not start, crank again and after 5-10 seconds press the accelerator pedal to the floor and HOLD IT THERE while you continue to crank for another 30 seconds ! It will likely start. The problem is a sticky Idle Air Control valve. Remove and clean or replace.