Had an issue with the car stalling on 2004 Buick LeSabre

replaced the mass airflow sensor, solved the stalling problem, but the vehicle still has some issues with running smoothly and not hesitatiing or seems like it is not hitting on all plugs. seems to be skipping, checked code on meter, mass airflow sensor, and gas cap, which was replaced less than a year ago. With both parts less than a year old, where do I turn to find out what the issue is?

Asked by for the 2004 Buick LeSabre
where did u buy air flow? if its aftermarket they suck and u may need to get it warranteed
Either OReillys or autozone, darn it, the great american way, make a big profit and hope the part works... thank you,
buy delco