Motorcraft carb/intake/maf cleaner or Kroil. Funny thing... Ford used to recommend Kroil (which is the best damn penatrant/cleaner I've used) and I guess they figured out if they recommended their own product they could make some extra money off this!

When I change mine (more often than most because they are subject to more extreme conditions under boost) I soak them overnight, then again 15-20 minutes prior to the job.