:doh: this is why you change your spark plugs one by one

In every car I've ever seen, the spark plug cables from the distributor are all different lengths - so pull them all out, and compare their lengths. Obviously, the longest one goes into the cylinder farthest away from the distributor and the shortest one belongs to the cylinder right next to the distributor.

edit: and while you're at it, change your PCV valve if you haven't in awhile and suck some seafoam into that puppy unless you've cleaned out the intake manifold in the past 30k miles. That's my every 30k maintenance ritual And welcome to HAN!