coolant looks nice and clean, also oil.
I will check for leaks and condition of coolant and oil.
I hunt in my memory, and have same moisture in top of the engine in my old bimmer(when getting cold outside, and also short trips), also today I remove CCV from my brother BMW and same gunk in hoses from oil separator.
On Yukon, to me seems to be from PCV accumulation into intake.
However, after some little tune (filters, oils, fpr, pump, spark plugs and cables, cleaning TB, and PCV) start showing P0420