Camshaft sensor

Replaced the camshaft sensor because everything led to that being the problem, including when the sensor got hot, would have to wait for it to cool down before starting the car. Now after replacing, it starts but backfires and won't stay idling. Is there a reset that needs to be done besides the code reset? BTW, the code diagnosis was too much gas not enough air. Or do you suspect a different issue? The fuel pump has been replaced. The gas tank was emptied and cleaned. Air filter changed. Spark plugs replaced.
The thing which may have caused this whole issue is the previous owner had been putting gas that was taken from junk vehicles and used it in the vehicle. Also, the vehicle was rolled once but I don't have any details about that, only that it didn't have body damage. Any ideas would be helpful, or should I just scrap it and forget about it?
I attached receipt so you are able to see the exact part replaced.