Mk 2 Octavia Vrs TDI Misfire / lumpy idle problem

Hi everyone, last week i bought myself a nice example Octavia Vrs tdi, im really happy with the car but once it starts to get up to temperature there is a very noticable misfire / lumpy idle problem which after a while clears completely, i did read somewhere that it is a common problem with the diesel engine but i was wondering if anyone could recommend anything i can do to rid the car of this issue ?....i would be grateful for any suggestions    Cheers Paul