I go through periods when it is harder for me to formulate my thoughts than others. Why? don't know. I suspect it might be a form of stuttering, but then again it might not. My dad does a lot of what you say, and I do know that he used to stutter. He is a very intelligent man, but he pauses in strange places when he speaks and sometimes seems to lose himself in the middle of sentences just to start up again. He's always done this. I heard also that people who have some forms of dyslexia do this, even if it doesn't show up in their writing or reading. Speech is a very complicated skill, and all sorts of things can happen with it.