Idling rough and now more times then not running rough no code what could it be?

Thank you for your question, As far as running rough and no check engine light there are several things that can cause this, The code PO401 and PO302 are rarely related to one another, The OBD -2 system is very accurate on this vehicle, however replacing parts based on codes and pattern failures is never a good option. The system does have the ability to go into much deeper diagnostic data through mode 6 diagnosis, this is basically serial data analysis and can pin point alot of underlying issues, The best advice I can give you is get full and proper diagnosis, then have the repairs done with a facility that backs there diagnosis AND repairs, possibilities are fuel quality, fuel supply, fuel delivery (yes they are two separate systems), intake tract issue, engine mechanical issues.

Could be an ignition coil, thermostat or a cylinder head gasket leak.