sbrewer

I had engine replaced in a 2002 Sentra. About a month later, I flipped the car(very lucky..no injuries). The car was towed home and fired right up however it sat for a few months (long story) then we had the windshield replaced and back on the road. The car ran great for about 10 miles or so, then started slowly losing speed and finally cut off. Smoke was coming from under the hood. After about 30 minutes the car fired up and ran fine. Days later drove the car again and went about 50 miles or so and the same thing happened this time the ses light came on. Advanced Auto says 2 codes....o2 senser(did not say which one) and temperature not coming up to right temp(said could be stuck thermostat)
Question...could the o2 senser cause the odd problem of stalling and smoking then running fine or could this be something from flipping the car? Any ideas would be greatly appreciated.
thanks
sbrewer