Found an article that states he had brain surgery for water on the brain from head trauma. That probably explains the 2018 FB posts in which he sounds quite lucid. ( http://thelifeandtimesofhollywood.com/tim-conway-missed-carol-burnett-special-due-to-possible-dementia/ )
An interesting article about his life: http://www.patheos.com/blogs/christophers/2013/11/tim-conways-hilarious-and-spiritual-life/
A quote from his book: “I think God has placed me in several positions, which I have found humorous. I find humor in life itself, and I can hardly wait to thank Him in person.”
What a wonderful quote. Once he passes he will have that desire to thank Gd back again. He will be whole again.