I wouldn't be surprised, if you took one wire at a time, off each coil terminal, that you will find the terminal and the inside of the wire, all black from arcing......if you do, sand down the terminal(*) that are dirty, apply dielectric grease to the terminals, before installing new wires.....should install new OEM plugs, too.......might as well finish it off with a new PCV, fuel and air filter(if needed).....