I have a 98 Aurora and I had a tune up done because it was running rough and having trouble shifting. After the tune upthe shfting problemwas worse, I can literally floor the gas pedal and not leave 1st gear, so I had a diagnostic done that said it had a bad oxygen sensor so I replaced both oxygen sensors and no change. Since then I've been hearing a clicking noise inside the car and the security chime will ding and the lights will flash three times every few minutes on there own without the car running so I've had to disconnect the batteryand as far as the shifting problem I can't get the check engine light to come on so I can get another diagnostic reading. If anyone has any suggestions I'd be happy to hear them, cause I am without a clue at the moment.