I have asked many people who stutter to say a sentence from any text. Repeat the sentence without voice by just mouthing the words. I have never known any stutterers who stuttered without voice. Stuttering only occurs with voice. Voice comes from the vocal cords. When the airflow becomes stressed it will decrease or close the airflow which I believe is the root cause of stuttering. This is how I became fluent and never had a relapse. I would checkout the books by William Parry who talks about the relationship between the Valsalva response and stuttering. It is not an overnight success but with knowledge and practice you have the potential to become fluent.