Q&A

Couple thoughts - first, the "code...to replace o2 sensor" sounds like a poor interpretation of a code. What code was it? There are no codes that tell you to replace a part; merely codes that help you identify symptoms so a good diagnosis can be performed.

Second - my guess is that your code was related to lean fuel running, which is measured by the oxygen sensor, which is why many just jump to the conclusion that it is bad. Chances are you are running "lean" due to a vacuum leak somewhere, which is causing your stall and your low idle. Check for that -- good luck.