V50 1.6D, intermittent lack of turbo boost
 

Occasionally my 1.6D V50 has a total lack of turbo boost and it just refuses to rev. The engine usually starts to pick up around the 2000-2500 rpm range but sometimes it just refuses to rev, even if I put the throttle to the floor. Backing off the throttle and reapplying it usually seems to cure it. It probably only happens about 5% of the time and the rest of the time it revs freely as expected.

I replaced the EGR Valve with a brand new unit about a 1000 miles ago so I know the issue isn't that.

Any ideas would be greatly appreciated.

Do you have any idea when fuel filter was changed last?also any stange ticking off injectors?