Q: 06 Saab 97x stopped running while driving

I recently had an O2 sensor replaced and when I got the car back it would wind up between 2nd and 3rd gear, it would change gears but wind up then tick and wind up again, it would also give a pretty clunk while it would do this. Today I was taking it to the grocery store and it just stopped running and I lost the power steering. I pulled over and tried to turn it on again and got no response. All the other electric works (radio, windows, lights) but it wont respond when I turn the key. Everything was running fine until I got the o2 sensor fixed. What could have happened?

My car has 162000 miles.
My car has an automatic transmission.