you may also need to check if there's a sensor to monitor the oil pressure to the turbo, which can be faulty that reduces the oil flow to the turbo. Also Check the Air Flow sensor as well.
Make sure the Air path is also clear.If there's a back pressure (Air) on the turbo,
I think there's a sensor or a valve connected to the computer (directly / indirectly) that regulates the oil pressure to the turbo which is not working properly. Could be a the CPU malfunction after all. ..
Good luck
Nizzmo Z