That all sounds like all too typical build up from the pcv systems that all cars have now a days.. The egr is going to be clogged with exhaust residue though, (dry flakey, looks like lava rock).

If you take the time to clean it up and worry about it, lose sleep at night and such, then I would install a catch can on the pcv system. The egr stuff, you can't really get rid of.