I have a 2013 ford focus. 146k+ miles. With all my cars, I would fill up when I hit 1/4th tank. For the last 10 months I’ve been broke and my gas tank is always under 1/4 tank and gas light on and I’ve run out of gas 3 times. 6 days ago I filled up my tank and used a gas treatment. When I started my car it immediately stalled. I had to start it 4 times before I was able to hold the gas pedal in the right spot to rev the engine. All of this was about 3 minutes. After I drove at least 7 times, I had no issues. Sunday my tank was at around 5/8 tank. I filled it up and the exact same thing happened again. So far I have driven at least 5 times, no cranking issues. Can driving for that long constantly on empty cause problems? My check engine light has been on before this happened. It’s reading as O2 sensor. There is nothing else wrong with my car. Thanks for your help.