Hey Maleficio, What year 928 are we diagnosing - Can you ask the previous owner about the issue ? Does the car seem to run OK in the open loop mode without the Oxygen sensor ? How do the plugs look, performance, fuel mileage, etc..... Are you saying that the problem only occurs at the top end of the performance curve - how often are you up there ?
Have the local police added you to their watch list yet ? There is one policeman in my area that always seems to be on duty when I feel the need for speed.
Michael
