I have the exact same problem. I am not sure if you are a Duratec or Zetec, so I am not sure if its exactly the same, but based on what you describe, it appears the same to me. I'd like to add to the details that I have observed this problem over the course of about 6 months in my car. It has no direct correlation with weather (happens in wet and dry weather), previous trip duration, or time between starts as far as I can tell. It usually remedies itself by the 3rd attempt or so, but it usually barely starts.
After turning the key to the crank position, the starter will run but it is as though the engine refuses to turn over. By the second try, if it doesn't start, it will sound like it started to turn over, but won't get going fast enough to not die. The third or fourth try is almost always successful. I don't have a tach, so I can't tell you if the needle moves when it almost starts. What on earth is going on?
