I'm new to the diesel scene, took my 300d in to have new glow plugs put in and a motor mount replaced and some other adjustments too. My mechanic let me have the car for the weekend while an air filter arrived for him to put in....I had about 45 minutes of wonderful driving and then my top speed dwindled and it begin to surge from stop signs on up to road speed....back to the mechanic the following monday, he checked out all the vacuum lines and connections in the engine compartment (some had been rearranged by PO or mechanic) well that hasn't solved it so...hopefully someone here has seen this solved and can offer the solution... thank you