Hello together. First of all, I’m quite a rental on the gebit Autotechnick. I would like to take this into consideration if your answer is correct. I try to describe my problem as accurately as possible. I changed the spark plug-bosch platinum on 29.10.2012 with my Mercedes C240 T-4Matic, Bj 09.2004, automatic, on 29.10.2012 (free me well-known workshop). Afterwards the car had a very undisturbed run and it even went out at intersections. Furthermore, there was the ride off and for about two seconds a *noise, as if you were suddenly driving over button pavers (ratters). Demand at the workshop which then checked the car (how, by what means, I don’t know), which then determined that the lamda probes were defective and these were then exchanged. Now the car runs better, but in my opinion still worse than before the change, it ran by the way perfectly. I have the feeling that it has less power, ” especially if it’s a little warmer (from about 10°C), then it feels like you are driving on a road that has small grooves in the surface at even intervals (tires have been examined by me and a car mechanic, perfect). The procedures mentioned *noises from time to time are still there for about two seconds. What can it be about? Where can I get cheap help (room Bremen, OHZ)? Thanks already for your contributions. rwolf007 Note: Spark plug change including spark plugs should cost 650,00 € at Mercedes. Together with inspection A a total of 1100,00 €.