HELP : Emissions Test Failure

["Hanley, David A" <dah83662@domain.elided>]

Here's the details...
CO 0.57% @ 850 rpm
HC 180ppm CO 0.97% @  3000 rpm

I had a meter on the O2 sensor and saw it fluctuate from 0.7 volts at
tickover to 0.06 at high revs. 

The car has done 40000 miles since it has the catalytic convertor replaced,
assuming they replaced the O2 sensor at the same time, would they really go
this quick ?

Is the above a sign that the O2 sensor is kaput?

Mileage is now 87000.

How do I test the heater side of it ? just check for continuity ?

Incidentally the 94 TS has a 4 wire O2 sensor, with the fancy Bosch
connectors (2), so I don't think water has got to the connectors, but I
could be wrong.

It used to stumble now and again when I bought it at 47000 miles, but that
seems to have gone now, maybe cause I drive harder.

Could it be something to do with the temperature sensor, I had the high
warning light come on intermittently a few weeks back, but the gauge ready
normal.

All assistance would be gratefully appreciated.

Regards
David Hanley
94 164 TS

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