Q: Bad gas flush fuel system 2015 Ford Expedition

If contaminated gasoline is suspected or proven, your only recourse is to drain, and possible clean, the fuel tank. The system filter would have to replaced as well and you have to hope nothing got past that filter to the fuel injectors as then those would have to be removed and cleaned as well. If you want to start out exploring ALL possible explanations, that is unless you have already confirmed that you have contaminated fuel, you can request an engine loss of power diagnostic. Whatever the cause (contaminated gas versus other causes), if you request the engine loss of power diagnostic, the certified mechanic will get this resolved promptly. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.