Hi,
Don't know if anyone can help, completely new to the forum, posting this on behalf of my Dad who is having a problem with his Subaru.

He has a Subaru Outback, 2009, manual, 5 speed, boxer Diesel engine, done 87k miles.
So for about the last 10k miles under heavy acceleration it hits a flat spot and loses power. Also at times will show a dramatic fluctuation in both revs and the tachometer. This will happen in all gears.

It's going in for a service tomorrow so any thoughts would be helpful.
Thanks in advance!!