In my own personal experience, psychedelics (mushrooms) have made me COMPLETELY fluent during the trip itself. I've also experimented with micro dosing which had the same effect. This is called the full-fluency phenomena, which currently very little is understood about. My assumption is that the psychoactive "dissolves" the ego for a time so you have little to no concept of how you're perceived. Of course if you're planning to trip, don't expect that your stutter will be cured forever, it likely won't. But it may give you insight about yourself, which is far more important to focus on then your stuttering anyways. (to be clear, none of this includes how to buy obtain or take drugs) have fun though :)