I'm having a recurring nightmare with my 2.1.

Was dying after first 30 seconds, overly rich like it was the O2
sensor. I replaced the O2 sensor with a good used one. It ran fine for
a week, then started the same thing. So, I swapped out the ECU and
temp 2 sensors. No help.

When I test this second O2 sensor, I hook up my digital meter (set to
2v) and it starts out at zero as the car warms and eventually tops out
and hovers (at idle) just over .800.

Is this right?

Jim