I have replaced the coil, cap and rotor. The wires I changed a few years ago, they could be bad. For the cost I'd wouldn't mind changing plugs and wires too, but it's very strange that it was driving fine when I parked it in the driveway and then the next day the thing won't fire. I would have expected some misfires, sluggish response on acceleration, etc.
But I've eliminated a sensor problem, timing problem, fuel problem, and it's sending spark, so it's just got to be a spark quality problem. Not enough juice or bad ground (cleaned and added new ground so that's not it) or bad wires.
Now the wires that I did check seemed to read fine, but if the boots are somehow suddenly gone bad, then the wire itself is not the blame. Gap could be off by a small amount, but the plugs I checked were clean and only open a miniscule amount.
I'm going to go with wires at this point. The main reason being that when I tested the spark at 20KV I got no spark, but arcing at the distributor wires. At 10KV I got spark, but it was still arcing. If the gap was bad but the wires good, then spark should have gone easily to the gap tester and to ground. It would seem that due to bad plug wire boots, the voltage is still finding an easy path to the other wires.
However, testing the voltage going INTO the coil will tell me if there is enough voltage to create spark in the cylinder. I've read where some cars arc at the distributor and it's considered normal, but in my experience, I've never seen or heard of it being a good thing.
I probably should get back to getting it fixed. The holidays made me want to forget about it, and I've been driving my other truck around. The Durango takes a LONG time to heat up and the steering is very stiff until it warms up a few minutes and you turn the wheel back and forth. Probably need to put some stuff in the PS pump to loosen it up.