If your timing and injectors are OK the most common problem is you dont have enough cranking amps in your battery. Di,s dont have any cold start aids and need a good spin to start them. Make sure your battery has at least 750 amps and is in good nick. A good quality lite oil is best too during winter starting.
If the engine is turning over OK and it has trouble starting make sure its not drawing air while standing. Most common problem is the flow return pipes from the injectors. Also ford recommend that the return pipe that goes back to the filter should be moved from N04cyl to N01 as that is the highest point as these engines are self primers.
Good luck
John Keith Roberts
November 2008