Q: Automatic 2009 v6 mustang idling roughly and/or stalling after new duralast maf sensor install

Occasionally, on a part of this type there are meaningful differences between aftermarket and OEM. Therefore, to simplify the diagnostics, the OEM MAF sensor (as vended by a Ford dealer) could be installed. Once you have an original equipment, genuine MAF installed, and thus have ruled that component out as a cause of the engine performance problem, OBD-II codes are read (if codes are still present), with freeze frame data, and the components identified in those codes are tested in turn. That testing is described in the "diagnostic decision tree" in the factory manual...quite a few steps to go through. Once all codes are resolved, if the problem persists, a rough idle diagnostic would then be performed and that, for sure, will resolve the issue. If you want the required, diagnostic steps performed by a certified Mechanic, dispatched by YourMechanic right to your location, please request the rough idle diagnostic and the responding certified mechanic will get this taken care of for you. If you have further questions or concerns, do not hesitate to re-contact YourMechanic because we want you to make the most of your repair dollars and help you to get the best possible results.