2006 C230 Sport Sedan slight Drivability issue
 

Hi All, I'm New to MB, but I do enjoy my recently purchased used C230 Sport Sedan. I do have one slight drivability compliant. Under "normal" acceleration from a stop, I notice a "flat spot" as it builds RPM/Speed. I did hold it in 1st gear & verified it is the engine...not the transmission. Again this is only noticeable under a normal acceleration, if I accelerate very slight or very heavy, no noticeable flat spot. I forgot to mention, it is a 6cyl. auto with 20,000 mi. on it & nothing but normal service records. Any thoughts of anything I can do, or have done would be much appreciated.
Thanks again'
Steve