Ford Repair: 91 Explorer, spark plug wires, quality plug

Question
I have a 91 explorer that is having electrical issues.  I started the truck and opened the hood, when it was dark, and looked at the spark plug wires where they meet the plugs and it was glowing blue.  I am loosing spark, and the truck is running like crap.  I replaced the wires already and they degraded after about 600 miles.  My next thought was the coils.  My Father asked the mechanic at his work and he suggested the coils.  The plugs are new.  Thank you, and I anxiously await your response.

Thank you
Nate  

Answer
I have never checked plug wires like you describe. Not sure if the blue is not simply the electrical field around the wire. Leaking spark is usually just that, a spark. If you used quality plug wires they should not fail after as little as 600 miles. Coil failures are not uncommon, wouldn't be a bad thing to replace it. There are plenty of other things that can cause the engine to run bad.