Oxygen sensor tells the engine how much benzina to stick in there... so if it runs out of puff and you have a faulty sensor, there is a good prospect that the two conditions are linked.
If it's not the sensor, then it would be a fuel delivery issue but more things have to go wrong for that to be the case, than for a single sensor (which you already know is faulty) to fail.
Regardless... you went to some trouble to get the diagnostic reading kit and then probe the car's brains for errors.. so whether the sensor is the cause of this problem or not... I don't understand why you haven't replaced it already.
Ralf S.
