My stock one did that when it was dying. I replaced it and it solved the problem. It should never get in the double digits, at least it never does on my car anyway. I'd say try a new O2 sensor either AC/DELCO or Denso NOT Bosch...
Awesome. Thanks, did'nt think it was ever suppose to get that low. Just trying to fix every possible thing I can becuase I know something is creating a hell of a lot of knock.