I think I have acquired stuttering. I was very fluent up til the age of 8-9. I acquired it around 4th grade, gradually increased in severity, until it became noticeable. I have two self derived theories for why did it happen. 1. I use to speak very fast during class. 2. I had a severe fever around that time. My own assessment is that it can occur in any situation no matter even if I have memorized the content. It is directly correlated to state of my mind. The more I'm stresses, excited, anxious more I stutter. When I am calm it improves a lot. When I'm alone loud reading newspaper, I can easily cross 180-200 wpm without stuttering. One work around I have got after seeing a speech therapist is to speak slowly, stretching words. I use it when I am stuttering a lot as a quick fix.