I'm hesitant to do so because most people don't seem to gel with what I say, but I'll summarise. This involves a lot of introspection. I suffered a bunch of traumas as a kid. In dealing with these as an adult with meditation/psychotherapy/psychoanalysis, every time I processed some psycho-emotional difficulty, my speech improved. So there is a clear link between emotional state and self-expression. But it's not all about repressed or current emotions, other factors include uncertainty, distractions, tiredness. After a fair amount of success improving my speech by dealing with my traumas (and the purpose was better mental health, not specifically improving speech), I realised that dysfluent speech arises as a result of some kind of inner conflict, i.e., some part of me wants to speak, and another part of me doesn't want to speak. This is the most simple distillation of the problem for me. Resolving the conflict resolves dysfluent speech. The thing is, all manner of things can cause inner conflict. It could be unresolved trauma, not being genuine (being dishonest or not true to yourself), being wary around certain people or types of people like authority figures, being distracted by things in the environment, too noisy an environment, too quiet an environment, someone simply not listening. Basiclly anything that disturbs the equilibrium of the mind. Some of these things are easy to fix - if it's noisy, go somewhere quite or learn to speak louder - while others require a lot more work. The big one for me, as I've said, was trauma, which affected my psychological self deeply, and has taken decades to process the worst of (largely because I avoided dealing with it for years). Dealing with all this, learning about myself, and moving towards authentic self-expression instead of how I thought other people thought I should be has been the most powerful means of fluent speech. It's less about speech (which is more of an indicator of how true to myself I'm being) and more about knowing the self and expressing the self authentically and genuinely. For every interaction that didn't go well, I think, what was wrong there? What was the conflict? Was it situational or psychological or bit of both? How could I approach a similar interaction in the future? Do I need to introspect more and resolve something deep in my psyche? Do I need to steer the conversation do get the other person't attention? Do I need to wait for the right moment to say what I need to say? Do I need to say it at all? Am I being myself or trying to force myself to be what I think someone else expects? Whatever the nature of the inner conflict, that needs to be resolved to make any progress. I suppose this kind of stuff is quite deep, not necessarily easy to apply, and is certainly no quick fix, but maybe it will help someone.