1.9TDI PD Stutters/Misfires

Hi, I bought a Skoda Octavia 1.9TDI PD Ambiente back in December. Now when driving it I have noticed it had began to stutter very briefly when driving but its a problem that doesn't seem to be going away, if anything becoming worse. Its almost like you have taken your foot of the acceleration quickly. I have tried changeing the fuel filter and air filter but no look as well as running fuel cleaner through the tank. It seems to be less comman if your giving it some boot but if your just cruising down the motoway or riding round town then you notice it and its often at lower revs. Any advice people, would be greatly appricated. Thank You