2007 eclipse gs 2.4. 188k The car is hard to start , misfiring rpms fluctuating. I can baby the gas and after about 4 minutes will settle out then It will run and start good all day till the next morning I have replace many parts , it keeps throwing p421 p431 codes. I have replaced all o2 sensors coils, spark plugs, coolant temp sensor ,maf new timing belt and sensor Could my cat be causing this?