Some 2015-2017 Ford Mustangs equipped with a 5.0L engine may exhibit an illuminated MIL with DTC P0300 through P0308 present. A noticeable misfire may or may not accompany these DTCs.
If normal diagnostics do not lead to a root cause, remove the intake manifold and verify that the intake manifold runner control (IMRC) plates move when the IMRC actuators are moved by hand.
These plates are visible through the manifold’s outlet ports. If the IMRC plates do not move when the actuators are moved by hand, the intake manifold should be replaced.