Regarding the first problem, I have seen camshaft failures cause an unidentifiable problem as such.
A friend had a 2003 GMC truck, 5.3 vortec engine. He had it to the dealer 5 times under warranty. New injector, computer, coil pack, plugs etc. Finally it failed completely after the warranty was out and ended up getting a motor because of it. In this case the roller on the lifter apparently failed first, taking out the camshaft and causing a cyl. 7 misfire code on the way. I hope this doesn't help, as I wish mechanical failures on nobody.
I've been told by supposed mechanics that a mechanical failure could not cause a misfire code, but they're wrong. JMHO.
Also, go back to the basics. What did the old plug on #2 tell you? Lean, rich, normal, excessive wear, etc? The four whores (Suck, Squeeze, Bang and Blow) always apply....and I tend to overlook that as much as anyone. Leaky intake manifold gaskets sucking air can cause this, faulty fuel injectors, valvetrain failures, low compression from a washed-down cylinder(from leaking injector), etc. I hope it's something simple though :P.
Check thoroughly for vacuum leaks. Brake cleaner(make sure it's not the non-flammable stuff) or ether is a valuable tool for this(spray suspect areas). Be careful to keep spray away from the air filter inlet, as this can give you a false reading. Switch two coil packs(if they're individual to cylinders) and see if it moves. This will ID a faulty coil pack. Switch fuel injectors(this will cost you a couple o-rings), this will ID the injector. If it maintains cyl. 2, run a compression test across all cylinders. You should be able to ID the problem by then, with minimal cost. Also, you can put a vacuum gauge on it. I don't know what a normal reading is on those cars, but a misfire may cause a fluctuation due to lack of scavenging on the misfiring hole.
I don't mean to sound like a know-it-all, just trying to help.