Since each pack fires two cylinders, when they miss it is real noticeable. I actually don't know the "by the book" procedure for testing these packs, but a coil's a coil, so you'd be looking for any open (infinite) readings across the primary and secondary windings obviously, but I don't know what spec for resistance is. (I don't have a manual for it)
And since temp seems to be an issue, you'd want to heat it while observing the reading, a hairdryer might work good for that, because it sounds like the test might not show you anything cold.
I've seen a few cases where a specific coilpack was breaking up, causing those two cylinders to cut out, but after replacing it the misfire continued. The problem then was in the ignition module, under the coils, and the internal circuit to that particular coil was failing.
I have sometimes been able to use an inductive timing light to "see" the ignition misfire and identify the cylinders affected, then swap that coilpack with one of the others and see if the misfire follows that coil to those cylinders. Then you know it's bad.
Thanks for the comments, Al! Yer gonna give me a big head.
