mbtech208,
I have a 99 clk320 that has an intermitent rough idle like the guy with the cl500 describes. Occansioally at idle the rpm's will drop enough that you can feel the engine idle funny. It does not happen all of the time.

Also,
When the car has not been started for a couple of days the first time you start it you hear a clap, clap, clap, clap. It almost sounds as though the internal parts do not have oil on them yet. I do have synthetic. The noise stops after about 5 or six quick clap, clap, clap. It is not extremely loud but does not sound right. It is more of a clump sound. I pretty much observed the break-in period (which different advisors claimed different things, some said break-in others said no break-in needed).

thanks for you help

 

If you let any car sit for a few days without being started, it's going to sound a little odd for the first few seconds while all the oil that has bled into the oil pan is pumped up again. Unless it's extremely loud or doesn't go away after 5 seconds or less, I wouldn't worry too much about it. As long as you're using synthetic oil, you'll be fine.
About the rough idle. Like I said, the Snoop Dogg's wife's S500 had a rough idle and a new mass-airflow sensor fixed that. There is also an updated ME engine control unit available for 112 and 113 engines with a rough idle. Since yours is a '99, it probably doesn't have the new control unit. That's about the only things I can think of off the top of my head.

 

Thanks mbtech208. My car goes in on tuesday to ge the ME update. I doubt they would have offered it if I had not mentioned that I heard of it.