2002 Trailblazer Revs High in Morning Now When Accelerating

My trailblazer has been sometimes revving high when I first give it the gas in the morning. Our Ford F-150 does the same thing. Once it tops out it usually fine except this morning. Now when I go to accelerate it wants to rev high before shifting to the next gear. It is an automatic. Any ideas?
Thanks

I have a suggestion. It might not be right, but it could give you a start.
It might be something called a fan clutch. My 02 LTZ did the same thing. I took it in twice for that same thing when it was under warrenty.
I hope this helps.