It is very difficult to say what your problem is but I would think if your workshop suspects the fuel pump then they must have very good reason to replace it as it will probably be quite an expensive bill they will give you. Ask them what fault codes they came up with. If the motor is running ok otherwise then without seeing what is on a code reader then the first place I would look would be your intake system and check for splits in hoses/intercooler connections etc and also the turbo itself for wear/play, did have one of these a long time ago and the turbo waste gate itself was seized, other than that you will have to ask your garage what the best way forward is. Good luck.
cdc
April 2016
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