Recap:... I had an intermittent problem with an O2 sensor, plus possible fuel contamination. Ran out bad gas, ran "sea foam" through vacuum hose, and put some into gas. Made O2 sensor problem go away and car ran normal..
As per Backyard's suggestion that O2 sensors aren't made to last forever.. I changed all four of mine. I had 138,000 miles on mine in a 96 coupe. Now car seems to be more responsive than before (when computer wasn't in limp home mode..) $290 for parts and 15 minutes on the lift.. Now when I do have a problem or get a code... and least O2 sensors shouldn't be a problem for a while... Looking forward to checking milage on next trip.. Chuck