Rough Idle
 

While sitting in heavy traffic I noticed a slight vibration and a small movement on the tach. I slowly reved the engine and it began missing around 4000 RPM. It runs great and pulls strong past 4000. I read the recall post concerning balancers and just checked. I have 112 035 00 00. Any ideas?
2001 production SL500SA ,R129 ,M113.961. A little over 51,000 miles:confused:

When there is a balancer problem ,you're likely not to know until it flies apart and tears up the timing cover and oil pan. If you're actually experiencing a misfire the ME2 should recognise it and cause a Check engine light.