Just recently purchased a 02 SLK320.Has been running smooth for last 4 months.Just recently developed a rough idle.Not as smooth as it was.It is not bad but I can feel it.Miles are currently 52k.No engine codes visible.I know this is a real open question but without getting screwed at the local MB dealer what could it be?Has anyone had these problems?My friends 02 ML had the same problems at 45k and it was wires and plugs.Is this normal.Thanks

 

Can't be too bad if there are no pending or stored codes.
Stuart.

 

Try a change of fuel brand.

Bazzle