I have a 1995 T-100 X cab 4x4 and I had a coil pack go bad once and the symptoms that I had was almost like the same symptoms as a bad spark plug. I know the coil packs are different and not cheap either. I think I paid about $ 85.00 for the bad one. I would replace all wires and plugs first and go from there. My truck started out missing and running rough at first and it was intermitting. It got worst and the engine light would come on also. I hope this helps I do have a chiltons manual but I have not seen the troubleshooting part on the coil pack.