Why did you replace all four O2 sensors?
Highly unusual/unlikely that all four failed at same time. When such is suspected it's usually the heater circuit.
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
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