2004 MCS, 125K. I replaced my plugs at about 100K and recently decided to also replace my original plug wires and coil pack, not because they were acting up but simply because they were old. Much to my surprise the coil pack terminal for plug # 3 was significantly corroded, probably resulting in a very loose connection to the plug wire. Any one else observed this? Any explanation?

 

common problem. I checked mine with 80,000 miles the #3 was corroded tried to clean it up with some emery cloth but the plug wire would not snap back on. I just ended up replacing it with a stock one along with the wires I got off ebay for $35 bucks along with a pulley puller and a stock air box. The coil and wires were brand new and the Puller was from minimania.

 

Coil issue with stock coil is very common...
Stock coil has an iron/steel plug that is nickel plated....
Most aftermarket ones are brass or aluminum....
A dab of dielectric grease on the plug will help prevent future issues.