In case someone is searching on the topic, here's some insight on the Intake valve carbon build up on the Ecoboost motors. It's NOT just a Ford issue or an Ecoboost issue. It's an issue for ALL direct inject engines, and even more so on direct inject motors that use a turbo.
The root cause is that since the fuel injector is now located in the combustion chamber instead of the intake manifold. The crankcase air that gets routed from the valve cover back into the air intake manifold (via your PCV) system still contains carbon and oil vapor.
In regular injected engines where the fuel injector sits in the manifold or upstream of the intake valves, there is a steady flow of fuel that keep the garbage from the PCV system in suspension or is able to wash the intake valves on a continuous basis.
Direct inject motors don't do this. So now, the vaporized oil and carbon is free to cake onto the intake valves. This problem is further exacerbated by the turbo because you also have higher pressure in the PCV system and this carries more oil vapor and carbon from the valve cover into the intake.
You can use an oil catch can to help reduce the amount oil vapor that is available to enter the intake, you should also do regular oil changes at 5K or 7K with full synthetic to reduce the amount of carbon that is available. However, neither of these will completely eliminate the problem. It will keep the valves cleaner longer though.
In the event the build up starts to cause misfires, there's only one way to fix it. Clean the intake valves. Now, I don't know about Ford, but I know for a fact that BMW has started to use a mechanical cleaning method called Walnut Shell blasting. Basically they remove the intake manifold and for each cylinder they do, they make certain it's on it's combustion cycle so that both valves are closed. They then take a specially fitted adapter so that the intake port on the engine is sealed and have a hose attached to high pressure air that gets fed...walnut shells. There is also another hose attached to the adapter that has suction and sucks all of the nasty stuff out.
It's like sandblasting but with walnut shells...Why walnut shells? because they won't mar the valve or head surfaces and won't do internal engine damage if some crap gets in the cylinder but, they are sturdy enough to clean the carbon off the valves.
To my knowledge BMW is the only one that has sanctioned this method for their dealers. VW has looked into it but no official word.https://www.youtube.com/watch?v=ONp6gQXpyKU
Ford should consider this method.
The only other method for safely removing the build up is by hand...scraping and scratching away at for as long as it take. For those that are familiar with how tough carbon can be...it can take hours by hand depending on the level of buildup.