What makes you think the coil is bad, besides the "random misfire" going away.
Have you tested the coil with a voltmeter;or dmm?
I have a feeling your wasting tons of money on coils for no reason. Test the coil with a dmm and check for continuity between both points where your plug wires plug into, if its O.L. or shows high resistance its bad. I can get you specific spec when I get to school tomorrow. We have ALLData Pro for free,
lucky for you I'm in my second driveabilty class where we test no spark, emissions problems, rough idle, etc. You know, drivability concerns.
I will get back to you with the coil specs, as well as injector specs for resistance.
If the misfire moves around, it really sounds more like a fuel pressure problem.
You did say you already replaced your plug wires? If not take a water bottle, and spray the plug wires with water, if you see arcing, you have faulty plug wires causing your spark to go to the least resistant path to ground, giving you misfire