dude your in the same shit hole as me, we both have the excact problem, replacing my o2 sensor this friday, if it fixes it i will tell you, also CEL goes off when i turn off the car, its ok for the 1st 30min of the 1st drive of the day, then it comes on again when i push it, so see same problem, same thing with the gas mileage, full tank will last me about 3days.... used to be like 5days...