moving rev counter at idle
 

1994 Euro C180. My rev counter is moving slightly from its constant position, and this can be noticed only if you look at it for a few minutes. The engine sound changes also very slightly if you listen hard. There are no unusual vibrations or jerks and no misfiring. Everything is ok, thank goodness. I have been away for a bit more than 3 weeks and when I started it, it fired straightaway. However when I drove off and slowed to turn a corner about 50ft away, it felt like it was going to stall when I stepped on the accelerator. I think I changed to S from E or changed to 3 and it moved off without anymore fuss. Don't know why this happenned. Maybe a cold engine, cold tranny, sleeping for 3 weeks? The slightly moving rev counter has been around since I bought this used car in early 2002. Your opinions will be appreciated.

How big is the fluctuation in engine speed? Slight fluctuations of around 10-20 RPM are normal, my M104 has always done it at idle. I don't think this is any cause for concern.