Anxiety triggers a stress response. The release of stress hormones increase heart rate, breathing, muscle tension, and our ability to regulate becomes difficult. Things to try would be practicing mindfulness breathing and body scan strategies. Start off in a calm place at first, but try to use these strategies everywhere you can. You want to practice until it becomes an automatic action so when you're in a stress response it can help trigger our parasympathetic nervous system (which is our rest & digest system). This may not reduce the frequency of occurrence of moments of dysfluency but it will help with calming your fight/flight response which can contribute to the intensity of those moments.