Yes, sugary + caffeinated coffee and energy drinks makes my stutter worse too! As soon as I stopped drinking these beverages, my fluency improved a lot. These drinks block adenosine in the brain and cases a surge in dopamine. This surge in dopamine causes even further dysregulation of dopamine in our brain, which worsens our stutter. I would say this means we already have a higher dopamine baseline and drinking these drinks pushes it even further out of whack. Some stutterers have a lower dopamine baseline and these drinks actually calm and improve their speech. If you notice it’s worse after drinking these drinks, then I suggest you refrain from drinking them if you have a heavy speaking day (or week) ahead.