would point to something upstream and/or common. So lets start with the AOS as a theory and take the air intake tube off and peer into the throttle body. If there is oil there, then it may be from a broken air oil separation tank or the hoses that connect it to the crankcase and the intake. And it may be overwhelming the OS sensors as it isn't burned in the cylinders and escapes to cover the sensors.
Link to a web page which describes accessing the throttle body
AOS
Air Intake info
Threaded Mode
