RazorbackMustang
MT82 Lover
DI engines tend to carbon up the intake valve due to the PCV system dumping oil mist into the intake manifold and there not being a conventional injector spraying down the back side of the intake valve. VW (also Audi), Mazda (Mazdaspeed 3), and Chevrolet (Cobalt SS LNF motor) have issues with this from what I have seen. I've owned 2 of these three and it was a known issue. Hopefully Ford got the PCV system right on the ecoboost.
Which is why I have an ENORMOUS oil separator on my ST. It's about the size of a one liter bottle. And it took 5 damn hours to install.