My sister's 97 legacy needed an upstream O2 sensor. I replaced it and cleared the codes with a scan tool. Now I keep getting moniters not ready. (catalyst and something else.) It's been over a month and over 1,000 miles. I've tried cycling the ignition, turned on the a/c, drove around in reverse, everything I could think of. Can anybody help?

The O2 sensors run their cycle while cruising at a constant speed above 45 or 50 mph. Mine reset pretty much as soon as I get on the freeway. If she only does in-town, short distance driving, maybe that's it...