Re: Spark plug test
I would unplug from the plug itself as unplugging from the packs can cause sparking and possibly mess up the coil (if it's not already).
Do you have a missfire? If so, you can either pull each plug out and look at them to see if it's the plugs causing it. If they are not fouled or damaged, than start pulling off wires one at a time. If they make the missing worse, then the wire you pulled is good, if it made no change, than that wire was bad and you need to replace it. There's no real way to test coil packs, some parts stores might say you can, but it is really a BS test, they could pass it for having continuity, but it could still be bad anyway.