When I noticed caffeine impacted my fluency, I’ve researched the affects of caffeine on the brain and read research papers discussing PET scans on the brain of stutterers compared to non stutterers etc…. There was also some papers discussing dopamine and the stuttering brain. You’ll have to look those up online. All I know for a fact is eliminating caffeine and sugar has improved my fluency a fair bit. I’m now thinking I’ll go on a SSRI to reduce anxiety and help “modulate” dopamine levels and see how that goes. 🙏🏼