My 1994 100cs wagon with 110,000mi. spent yesterday at the dealer here in anchorage because of the check engine light coming on after I've driven for awhile at which point the beast stumbles a bit & then continues on its way. After 2.5 hours thay are unsure whether it's co2 sensor or cat converter. It feels like co2 but I am beginning to get the burning egg smell when I stop the car. CO2 has never been replaced. Is there only one co2 sensor? The light always goes off when I restart the car.

I've had almost exactly the same thing happen to me. First the O2 sensor went sort of bad (it would only trip the Check Engine light after drving at highway speeds for a few minutes). Then the catalytic converter started to rattle (breaking apart inside). There's a chance that the sensor was causing the car to run too rich and got a bit of gas in the exhaust speeding up the deterioration of the cat. Have the sensor(s) replaced right away - they're a _lot_ cheaper than a new cat.

-Jim