The blaster coil is what sends the spark to your distributor. The fifth spark wire that doesn't go from your distributor to your engine is connected to your blaster coil. I don't know if that could be it, but check your sparks as well...make sure they are all blue or else you aren't gettng a strong enough spark to ignite the fuel causing the misfire.

http://www.msdignition.com/coil_blas..._8202_8223.htm