I am kind of thinking that the sensor data seems to match the engine sometimes, then other times its just totally off the wall either stuck on a value, or bouncing erratically. Could this be a bad O2 sensor? It might have 5000Km on it. ACDELCO AFS109 purchased from RockAuto in October. For all I know, it was always acting like this. The car has not been in decent running condition since last summer.