Codes P1300, P0300

1999 9-5 This car began to get diagnostic trouble codes P0300 (Random Multiple Cylinder Misfire) and P1300 (Manufacturer Control or Misfire) a few months ago.

I can reset the codes with the OBD reader, but they continue to come back.

I reset the codes when the car is warm, and they seem to come back the next time the car is started when cold.

The car runs fine with no noticable ping or misfire or loss of power.

Any ideas?

Thanks