I have a 2001 c320 w203 model, which has has developed a misfire and is juddering badly.now in limp mode, the car was recently serviced and the plugs have just been changed. So im not sure what it is. Any help would be appreciated.
If the garage did not remove the plug leads carefully then they could have broken the internal core and this may be the causei of the misfire, the leads are usually very tight and Mercedes have a special tool for removing them.
The judderiing is probably because the ECU has shut down the injector on the cylinder that is misfiring to protect the catalyric convertor.
Go to the garage that did the work and get them to check it out, if they do not have the STAR diagnostics then a standard OBD reader would still be able to scan for the fault code(s) and would also be able to read the freeze frame data of various engine parameters the ECU would have recorded at the time the misfire first occured.