Mercedes-Benz CLK430 OBD2 Code P0300: Random Misfire After Spark Plug Replacement

Hi, I recently received a check engine light diagnosis showing OBD2 code P0300 on my Mercedes-Benz CLK430. The code indicates a random misfire across multiple cylinders. Although all spark plugs were replaced during a routine tune-up, the issue persisted. The vehicle was already experiencing misfiring prior to the service, but installing new spark plugs did not resolve the problem. Interestingly, after the tune-up, the engine light activated, and while the engine performance improved slightly, the underlying misfire remains unresolved. I'm seeking advice on potential causes beyond spark plug failure, such as ignition coil issues or fuel system problems, especially given the persistent P0300 code.