Jundi_Ahmed1 i'm having the same problem as well. I have a 2004 clk as well. Have you found a answer to this. If you have email me. [email protected] Thanks i have a 2004 clk 320 after driving for a while its rpm sometimes shivers and the car shakes like its about to turn off unless i hit the gas peddle a bit to take it back to normal what could this be from?

Sound like the ISC actuator it part of the throttle body, and its a reversible motor, it maintains idle speed stability its a motor actuator,and is part of the throttle body but just dont condemd it sevice the throttle body this acuator motor sometime has a hard time moving to adjust RPM.Then there is the MAF(mass airflow sensor) even though this measures good or bad it does not set a code or Check engine light,
Here the most probable cause MAF they have problems on MBZ CLK 320 and only a fuel trim reading can detect problems with this sensor, dont be dependent on ck eng light it wont show, then there is the MAP manifold air pressure after coming to a stop sign the EGR may still be open and not close properly causing the stumble and this wont give a code. So here is the most probable cause the MAF mass air flow going out of range causing lean fuel trim or the EGR pintle not closing properly stumbing the vehicle , so I leave you with MAF or EGR either one or the other or both or just replace both