06R500

I just recently purchased a 2006 R500 with 42,000 miles. I am a first time MB owner and have a few questions regarding the car:

1)I have had the car for 10 days and am now noticing that my RPMs at idle are around 600. I am almost positive that on day 1 they read around 1000. What should the RPMs be? I am also noticing that the engine is running a little ruff. I can feel a vibration on the gas pedal. Is this normal?

2)Should I bring it to a certified MB dealer to have it checked out?

Thanks in advance for your responces!

R KLASSE

See my thread after you read this, anyway my '08 R350 basically the same motor just short two cylinders had a rough idle when stopped at a light idling. I could feel a subtle vibration too. Anyway, my car has 35K miles but had done this ever since we had it with 25K miles. My car is currently at Mercedes awaiting a new cylinder head due to a stuck or bad valve. I hope this helps, I'm not happy about it but glad I have the CPO warranty and that Mercedes has taken care of me.