Ford Repair: F-150, coil pack, water stain

Question
I have an F-150 1998 4x4 4.6 eng.
It developed a code PO-302 Mis-fire #8 cylinder.
What is the most common reason besides coil pack and plug wires?
Thanks

Answer
po302 is number two cylinder misfire-most common is coil but that don't mean that's what your problem is-number two is second plug on passenger side they are bad to get water in that cylinder-check plug boot and plug for water stain-if you find cracked plug be sure and replace plug boot also because there will be a carbon crack in boot and it will crack plug in same place.
coils are common and inexpensive but bad plugs can take out a coil so change it also.