My 87 Syncro GL was idling poorly and had some driveability problems.  When 
it was warm it would "buck" a little at low speed, had poor acceleration, and 
hesitated a little.  This morning, about 5 minutes after I started it up (it 
was warm by then), it "bogged down" as I accelerated and seemed to be 
"flooding". I shut the engine off, waited a few minutes, restarted, and the 
engine was back to "normal".  After I disconnected the O2 sensor, it idled 
rock steady, the bucking went away, and seems to have decent acceleration.  
Is the O2 sensor bad, or are there other problems?  

Thanx in advance.

Steve M.