what causes miss fires in Altima 2003,also would a defective cat converter cause on 2003 Nissan Altima

coil 1 and 2 have been replaced, codes 042 and 300 keep coming up

Asked by for the 2003 Nissan Altima
1 answer
seek diag and est as it could be several issues,a plugged catt would cause misfires and lack of pwr