Does the cel come on intermittently. Before changing my o2 sensors at 100,000 miles, I would get a cel usually on the highway. It would go on and off every minute or so. On my obd 1 system it was codes 172 and 176 if I remember correctly. After I changed the front sensor I did not get any cel's. But I changed the rear one anyway, major pita.
About the fuel regulator, as far as I know if it is bad the main problem you will get is surging.
And finally, the o2 sensors would not cause a loss of power at wot because the engine doesnt't use the reading from them at wot.
