I also noticed that behavior with my account. I would unfollow all my friends, so my news feed was only posts of the pages I liked. After a couple of days, posts of my friends would start creeping up again in the news feed.

That was when I decided to deactivate my account, and it's been the best thing so far. The account deactivation form is scary, Facebook practically begs for you to stay. I don't miss it at all.