Can u loose power from a bad o2 sensor?

 

Yes. But then half a dozen other issues and/or bad sensors can cause that too...need more details on the car conditon, service history etc...and despite what you might think a lot of these don't throw codes. I had my car run like garbage for months after a spark plug install only to find the ECU decided to retard my timing...not sure why, possible bad sensor somewhere. Remember the car ECU only tunes the car as well as the inputs its getting. Or you could have ancient plugs or another maintenance issue