Forester poorly, please help.
 

Any help will be greatfully received guys / gals.
My 2004 reg 2 litre XT recently suffered a turbo failure after 70 k miles(the impellor fell off one end and the other end lost a nut). I've had it replaced at a garage with a new Subaru relacement unit. However the car is still not right, which leads me to suspect the turbo failure was a symptom of another problem rarther than a one off event.
When the car is initially warmed up all is fine at low speeds (up to 50mph) When I give it a bit more it starts to play up. When cruising on the motorway the car starts to loose power and emits a whining noise rather like the turbo is catching. Also, once this has happened the car starts to suffer similar symptoms at lower speeds usually on bends and roudabouts (strangely). However, this might be down to accelerating in the lower gears ie the revs are higher.
The car had new oil and a filter when the turbo was changed. What could be causing this? The engine is otherwise fine, no rattles etc. :cry: One theory is a dirty oil feed line to the turbo??

Bump.

Any advice guys?
I've got the thing booked in on Saturday but am curious as to what the problem is.
What could cause the turbo to squeal, i'm thinking poor lubrication of the bearing maybe due to a dirty oil feed pipe?