Does it turn over and just not start, or does it not even turn over?
If I remember correctly, my electronics teacher in high school said you lose about 25% or 50% of your battery power when it's cold out. Not sure which.
if it is warm out but the car has been sitting for more than 8 hours will it start ok?
if it's cold out and the engine is warm will it restart ok?
now i want you too try this the next time it is cold out and the car has been sitting..
turn your key too the run position but DO NOT START the car.. after 5 seconds or so shut it off and do this again.. repeat a couple of times then try too start the car..
some fords have had problems with fuel presurse takes a minute too build up.. what i said too do above will run the pump and build presure in the line.
now i assume you mean a extended crank before starting.. if it will not start at all on cold days then the problem si somthing else.