I liked what you said; Not afraid of talking, afraid of stuttering. Regardless the reasons of why we block, the blocking itself has it own consequence. Whenever we block talking with someone it creates a weird moment. The person listening does not know how to react and the person who is blocking feel´s like a weirdo. Because of the negative emotions associated, the person who blocks try to break the block only giving more power to it. It is a tricky trap that we fall for it everytime. Later on, we develop a fear of stuttering as you said. In our minds we think that we will look like idiots so we do whatever we can to avoid stuttering. I can think of two ways of improving the situation. 1) Full acceptance and completely honesty about our blocking will prevent for us falling in to the trap. 2) Changing our belief about us looking weird or stupid because we have a stutter. A more acurrate belief could be that we look like struggling. But going from there to stupid is just wrong.