Google this site its either the egr valve which is dirty or more than likely the turbo actuator very expensive and a very very common fault.I assume you have checked all the hoses for leaks ,Ford / Jaguar will not sell the turbo or actuator as a seperate item as they say thay need to matched as a pair some people have had some luck in just repairing or replacing the activator.

Edited by Collos25 on 09/02/2013 at 09:08

They are produced by Garret for Ford and the actuators are produced by Marnello most turbo reconditioners will not touch them and I can understand why as they need to be matched together according to Ford,I have had some success putting two 500ml bottles of Fortes commercial only turbo cleaner into half a tank of fuel.When the problem is in the actuator then its anybodies guess to what to do.I have replaced umteem combined units on Jaguar X type diesels and used to have a good supplier of units from nearly new crashed cars but this supply dried up.Early Mondeos used a vacuum actuator which was problemless but they changed onto electronic actuator when the produced the X type to try and gain some extra BHP .