When I did the plugs and wires it fixed it for me. It still idled rough. So I poured a can of seafoam in to the gas, and drove it around. After a tank or two my idle smoothed out. Maybe just drive it before you start replacing O2 sensors. You can also just check the resistance of an O2 sensor to...
I've got a similar problem at around 2K, but I haven't started to dive in. Most of what you've said is what I would have checked so you've got me a bit worried. Fuel pumps and injectors are the next things I would be looking at, but before you go down that road run a can or two of Seafoam...