C230K 6sp Poor acceleration
 

I have a 2002 C230K with a 6-speed manual. I have experienced intermittent poor performance in regards to acceleration. It appears that the supercharger is not functioning all the time. It has only worked well for a total of 4 of the 32 days I have had the car ( not just the first 4 days). The performance difference is dramatic. For instance, in fourth gear when you step on the accelerator there is a surge of power when it is working properly. When it is not, there is a noticeable lack of surge. The better performance happened two days after I added a fuel system cleaner additive. Since then it has reverted to the poor performance so this could be just a coincidence. There also is a noticable carbon deposit on the tailpipe. To date, the MB dealer has not been able to explain this or fix the problem. Has anyone else had the same experience and have you found a solution?