You've perfectly described my stutter, or as you mentioned, more of a block. What I've learnt, is that if I'm talking about something I'm super passionate about. I rarely block, and that's because I'm using a different part of my brain. I don't even have to think about it. But, as you say; if I'm talking about something that I haven't thought about. That's when I struggle the most. I've put it down to one thing. Preparation. And, I don't just mean preparation for what I'm talking about. I mean: sleep, diet, breathing, exercise, education. If I tick all of the above every day, I'll have a good day. Trouble is when you don't know what you're going to be asked. And so, get prepared with easily accessible answers to questions you know nothing about. Then, you won't have to think about what to say ever again.. well, not really. But it helps. In my head, I'm slowly becoming the most useless but prepared superhero ever. And you know what? I love it. It means I'm excelling at work because I have to try harder than everyone else to learn the shit out of what we're doing just so I don't block. How bittersweet is that? Anyway, good luck. Could talk about this stuff for hours.