Right, i doubt your turbo needs replacing. It is more likely the boost line which runs from your pump up to the turbo.
Looking face on at the engine, you can see your fuel pump on the left hand side of the main engine, under the PAS pump. On the lower right of the pump, you will see a short rubber pipe which is joining a metal pipe. This metal pipe runs around by the side of engine and to the turbo. This pipe is know for splitting and causing poor mpg, lack of turbo etc.
Will cost under £20 to do yourself, £40-50 by Rapid Fit at ford.
J P Evans, March 2006