Obd2 code p0300 on mazda protege 2002

Just had one of these with a maxima, the code is multiple random misfire, when a misfire occurs, to start is do the basics, replace the plugs, check fuel pressure, clean throttle body, and coolant is topped up. also I have seen if the O2 sensor is not working correctly is can cause a misfire, you will need a scan tool to look at what the O2 sensor is doing, o rby back probing the sensor (don't damage the O2 sensor wires). If it wires replace them as well, if it has coils they usually dont give that code if one fails, it will pinpoint that a certain coil if one fals.