Getting codes 0300 and 0128

[ebang]

I have a 2002 Montana, the check engine light keeps coming on, I recenltly hooked up a code reader and got these codes, can someone please let me know what these mean.

thanks.

[ctwright]

The first code you gave p0300 is for multiple missfire and the other is related to your cooling system. www.obd-codes.com/p0300 and www.obd-codes.com/p0128

[ebang]

thanks for the responses....I was meaning to change out the plugs and wires....guess I'll change out the thermostat as well.