intermitent rough idle (320cdi)

[basssman]

Hi, I've noticed a rough idle on my 320cdi W210 (2000). It does'nt happen when the engine is cold only when hot and then only 50% of the time. It seems like only one cylinder but it makes for a rough idle. Does anybody have any ideas about tracking down the fault? Would it be worth trying injector cleaner etc?
The car has only done 65000 miles and ran smooth until this.
Any thoughts would be appreciated.
Mike..

 

[Parrot of Doom]

I would have the codes read as a starting point.