My coil pack cable was arcing to my crankcase breather, causing a misfire. Its the grey wrapped cable under the blueish hose in coppereclipse's sig pic.

Also, I have magnecores, and they misfire if they're not seated PERFECTLY. I have to smash em on there until my fingers turn blue and then twist and grind them on. I've seen plug wire lube that is supposed to increase conductivity, dunno if it'd help tho.

My plug wires also seem to arc to my head if the wire is resting on the valve cover. I put them in wire loom and bent it so they don't get too close to the hood or the valve cover.

Oh, and it's not the 02 sensor. You can completely unplug the thing and your engine will start running like crap, but it won't really surge/backfire like you guys are describing. Just run consistently like crap as if you're towing a house.