diagnose lack of power?

Hi
1.Try some diesel injection cleaner,and follow the instructions on the can.
2.When was the diesel filter last replaced?(should be no longer 12 months or approx 10,000 miles)
3.When was the timing belt changed?(replaced 3 years or 60,000 miles)
These are the main problems to a diesel not performing properly

big fat disco
January 2008