[a2-16v-list] OXS problem??

[Steven Arguello]

Ongoing (year+) hesitating/misfire under load. Did all the tests in  
the Bentley (again). DPR current  10.3mA no fluctuation. New O2  
sensor, and I even tried putting the old one back. Before I buy a 3rd  
sensor, I wanted to double check. How is the O2 sensor ground?  
Through the pipe/manifold? Any chance that grounding might be the  
problem?
thanks,
Steve