Get a partner and both take turns speaking on whatever topic.
Every time one of those verbal placeholders like, like, you know, etc gets used, do 10 pushups or situps or whatever.
Keep doing this until you can go 5 minutes without transgressing. Then the habit is broken.
It is amazing how much smarter people will assume a person is if that person doesn’t verbal placeholder all over their talky talk.
My problem is less verbal placeholders and more that I tend to pause all the time trying to pick out the right word.