turbo problem

[mick1983]

hi, a couple of weeks ago i realised something was leaking under my car.i took my volkswagon passat to a mechanic. he plugged in the computer and told me that i have a turbo fault.he seemed very unsure which has led me to ask the question here....

when i drive my car on the motorway its fine up until its gets to about 70mph.after that the car struggles to go above that speed even when ive got my foot on the accelerator all the way down. ive had the problem a few times picking up speed in side street. underneath the car some fluid id leaking. could this be a problem with the turbo or air flow sensor. i have vw passat 2001 1.9tdi. plz can any one assist me?thanks