Hmm...the mechanical problem (engine choking) sounds like it might be a carbon buildup issue. I've got the same year, model, and engine as you, and at the 74K mile mark (or thereabouts) it got to where it wouldn't idle. The dealership cleaned it all out but NAILED me on labor. The procedure for carbon cleaning is on the CEG site, however, and sounds easy enough for most people to do.
As far as the code mess...that's weird. I'd do the engine cleaning, reset the computer, and then see what happens.
