93 Altima:

Failed on high HC (.64gm/km), replaced O2 sensor, plugs, air filter and 2nd
test was WORSE
HC was .67 and CO went from 5.5 to 10 and Nox from 1.03 to .61 (Nox was a
pass)

I did test the new O2 sensor with a voltmeter and it ws much more response
that the old one but possibly defective?

Normally after changing the O2 sensor HC and CO drop by more than 60%

Car is running well, idle a little rough

Any ideas appreciated