Danny Mac is right on.

Aside from that, return that K/N air "filter" ASAP. It's going to let a bunch of crap into your engine. The holes are much larger in it, and the oil that's supposed to help filter can be sucked into the engine once it gets a little dirt in it.

You can directly check the O2 sensor's output and see if it's rich or lean by putting a multi-meter on the lowest range and checking to see if it sweeps between each extreme (0.1-0.9V) and spends equal amounts of time in each area. If it's a higher voltage, that should indicate a richer mixture and a lower voltage indicates a lower voltage.

Good Luck! Sorry for the short post.... those Tanqueray and tonic's caught up to me faster than I expected :P