This post of yours slipped by with no replies, but presumably you checked the FAQ setion

http://www.contour.org/FAQ/FAQ.cgi?s=probs&display=checkengine

and found out you have bank 1 (rear) O2 sensor problem. The most difficult to replace.

You story continues here:

http://www.contour.org/forums/ultimatebb.php?ubb=get_topic;f=3;t=008386

98 Mystique LS v6 atx 110,000km
97 Contour LX v6 atx 125,000km
stock CD on LS, cass on LX
spoiler, tinted windows on LS only
4 wheel discs on LX only
All other available options on both