When 1 coil goes out, I recommend replacing all of them, especially on a Ford/Lincoln. They tend to burn out at around 90k. Each coil goes for about $75, so figure about 1/2 hour ( say $50 ) per bank of cylinders plus the number of coils.
my car has only 45,000 miles on it, they said they had to remove the manifold to get at it, replace gaskets, cost me 600 dollars twice, am I being ripped off from my Lincoln dealership? Why didn't they replace all of them the first time?
if there is oil in the spark plug wells then you would need to replace the valve cover gaskets. i just had to do this last year and it was tough, but do-able. the oil cause the coil to fail, so if the valve covers aren't done the coils will continue going bad. hope this helps. if you need any info contact me at firstname.lastname@example.org