Subaru Repair: 2001 Subaru Outback Idles rough, poor acceleration, stalls at stop, subaru outback, gauge readings

Question
QUESTION: 2001 Subaru Outback Sedan was running fine until I ran the gas tank to empty and then it began to hesitate when accelerating (have poor response to the gas pedal) and idle rough at stops. I had a tune up (spark plugs & wires air & fuel filter) and fuel & valve service done and now it has begun stalling at stops and still has the hesitation issue and rough idling when not stalling. It always starts right back up. Any suggestions what to try next (ok, not running it until the gas tank is empty, I know =) ?????
ANSWER: Did you run it out of fuel?.I often see where my customers correlate it being very low on fuel to a drivability issue.But usually the case is that the state of the level of fuel was low when the car started to run poorly but the car isn't running poorly as a result of the gas level being low.I hope that makes sense. Its always good to monitor the vehicles gauge readings when it acts up but the answer may not always be that simple. Anything is possible i wont say that a fuel pump CANT be damaged as a result of low fuel levels just that its unlikely. But would be quickly ruled out with a fuel pressure and volume test. Any ways i would imagine by now the check engine light has set.Typicaly i have replaced quite a few O2 sensors on that year Outback.But in reality the car should be Diagnosed by someone who knows Subaru.

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QUESTION: Thanks for your response! Yes, I had run the tank dry and the problem started when I fille dit back up again. I never had this problem before I ran out of fuel. Even when the tank is full it runs poorly. The check engine light is on and reads Co2 sensor, but I have been told that the Co2 censor wouldnt casue the idle/stalling problems? Do you think running the tank dry could have caused damage to something other than fuel filter etc I have already replaced? I want to get her running well again & am hoping someone can tell me what it could possible be that needs fixing on it, THANKS!!

Answer
If you have a bad O2 sensor the vehicle can run poorly all the time.There is no CO2 sensor But there are two O2 sensors.The ECM determines how much fuel it gives the engine based on the O2 sensor readings.But there is no feasible way the o2 sensor which screws into the exhaust pipe could have failed as a result of running it out of gas.I really think to put your mind at ease on the running it out of gas thing you should perform a fuel pressure and flow test or have that specific test done at a repair facility.Please remember that the check engine light is trying to caution you that the ECM has seen a problem and it wants you to address it.Before there is damage to your car and OUR environment a car that is running poorly is causing a much higher level of pollutants then a car that is running properly.