out in the car earlyer and it was running like a bag of shit!

The turbo(t2) was spooling up like a bastard at under 2000rpm?
Running rough on tick over and when driving when you put your foot down it seemed to bog down for a second and then slightly picked up again.
Did notice the dump valve( yes i know they're not good on cvh, but the missus likes it ) has been letting air escape rather then dumping it.

It was fine when last driven just come on over night.
Any idea's? Hoping just an air leak but any info would be welcomed