I had this exact same problem with my 92 Sc400, with 99k on it. Turned out for me, it was both my front O2 sensors (which are a !Removed!, to get to). I attempted to change them myself, (and I had a lift, which made it 100x easier) and quickly stripped them both out in the process of removing them. I did this after soaking them in wd-40, and I am a farily competant auto mechanic, I like to think. I eventually had to pay one of my buddys that is a Lexus technitian, to come re-thread them for me (which I probably could have done on my own, but I had already botched the job enough I figured). Parts cost is about $140 per O2 sensor.
As far as the Traction control light, it will always be on whenever the check engine light is on, and the traction control will not work. If you want to reset these lights simply unplug the battery for 30-40 minutes, and the lights will probably stay off for a day or two.
So, if I had it to do over again, I wold have just taken it to Lexus, and not had to worry about it. I wasnt the easiest job Id ever done, although it didnt sound to tough to begin with.
Good Luck! :D