i have a hyundai matrix car on 2002 Hyundai Elantra

I did the system checkup last week and it shows 4 misfires. like cylinder misfire

Asked by for the 2002 Hyundai Elantra
could be plugs or other issues. seek proper diag and est
thanks. these are the misfire codes: 0121, 0300, 0301, 0303