I did a spark plug change as my mercedes c230 2006 272 engine are approaching 60k miles. Bought this car used, so not sure when was the last time the previous owner did it. Do my oil change regularly following the manual and checking air filter, cabin filter. Recently, i did a spark plug change, bought the Bosch plat YR7MPP33 from advance auto part. I check the manual it's recommending Y7MPP33. not sure the differences. I installed the plugs, and now the check engline light is on with code P0300 random misfire, and Misfire on cylinder 2 and 5. Also got a code for P0128(thermostat below)<this code already happen before spark plugs change. and 2 more codes saying that the Car is running rich on idle. The car vibrates during idle and car run like as if it lost tons of power and wouldn't accelerate that much. the vibratation smooth out when accelerating but goes bad as soon car comes to a stop or idle. So i went back to check for cylinder 2 n 5 to see if spark plug went bad or something. It doesn't seem like it went bad. Now i'm thinking it's probably a vaccum leak as it runs rich(more fuel than air). I'm not sure if that different spark plug with an extra R ( i guess resistors) would make that much of a difference or maybe it's just a vaccum leak somewhere. or an ignition coil went bad, throttle body not clean, dirty/faulty MAF sensors. I don't think it would be the fuel filter( running 93 fuel all the time and chevron fuel injector(every 3k)) . Any clues would help. Today i'm checking all the tubes to see for any leaks.