I started smoking just a few years ago after I left the Navy. I have noticed a little more fluency. I think it's because you become more present on marijuana and the witness to your thoughts as opposed to identifying with your thoughts. And I find my insecure self-talk is the main determinant of how fluent I am. It certainly depends on how much therapy you had in school(I had quite a bit) and the severity and nature of your speech patterns. And this just worked for me, but I try to speak with a full breath(which is so hard because my mind moves so fast). It helps if I meditate every morning and read books on mindfulness(The Power of Now by Eckhart Tolle is a great start, but anything Watts is good to). It seems like from reading this you feel you need the herb for something or to give you something you can't get otherwise. And really you gotta understand you're exactly what you need to be in the present moment. Work on yourself internally and your external world will reflect that.