Are my O2 sensors toast?

[njonesn]

Need to remove them and try to clean them however 2000 2.7 Boxster.
MAF is suspect, I have another on the way.

At idle the oxygen sensor voltage on both (pre-cat, no post cat on this model), drifts out of the 0.2 - 0.8 volt range.
Could one or both be faulty?

I'm trying to trace a rough idle and 'smell' or rich running.

Voltage snapshots over a few seconds.

Bank 1: 0.14, 1.00, 0.96, 0.15
Bank 2: 0.82, 0.08, 0.25, 0.82

Thanks.