misfire on 3.0 v6 code is confussing

my 01 escape with 3.0 v6 has code that comes up as po351. the code list says it is the primary coil ?? my engine has a coil pack on each plug so what am I not understanding here ?? it does not give any one cyl. as a misfire. this only happens when the temp outside gets to around 20 degrees.

I usually don't post links for other forums, but just about every option was discussed in this thread.
http://www.ford-trucks.com/forums/576951-touble-code-p0351.html
Either bad wire or bad pcm seems to be most common if you already swapped coil and plugs.