2002 Focus Cold Starting

My 2002 Focus Has problems starting and running when it gets very cold (5 degrees and lower).It has been towed to the dealer 3 times since it was new.It will start ,run for a minute and then stall never to start again until warmed up inside the dealers shop The second time it was towed they replaced the fuel filter which was not due for change per the service schedule.This time they told me it was the spark plugs which were fouled and had a musty smell (not gas fouled)also not overdue on replacement.It is not a cranking problem as it has a new battery.It also has 52,000 miles .Anyone else having cold weather starting problems?? or any suggestions,Thanks