Let me start by saying that my stutter is waaaaaay better than before, and that like you, I noticed that my breathing was a big part of the issue. I actually had almost the same train of thought as you. I felt that my inhale via my mouth was wrong and part of the problem. To the point that I was going around asking people around me a very stupid question, “How do you breathe when you talk?” It felt stupid because most people really don’t think about it at all, and they don’t have a good answer. They just talk and breathe completely naturally. But for me, that was definitely not the case. I was seemingly always running out of breath between sentences. In my case, what made matters probably worse was that I’ve always been a mouth breather, perhaps partially because I’ve had bad seasonal allergies since the age of 13, which made it impossible to breathe through my nose for several months of the year. And over time, I just completely stopped using my nose to breathe as it seemed easier to breathe through my mouth. Another stuttering symptom I had was a tight chest when talking, also due to poor breathing skills. Okay, so with that out of the way, some things I focused on to help: Discovered neti pot (salt water nasal flush) for my allergies. This helped unblock my nasal passages to help with nasal breathing. Started trying to consciously breathe through my nose as that’s actually how we were designed to breathe. I can’t say that I’m a 100% nose breather now, but I think that actually trying to become one is useful from the perspective that it makes logical sense that if you can breathe through your nose that you would be able to speak continuously without having to stop for air. When I was purely breathing through my mouth, I was definitely being forced to stop talking and take a quick breath through my mouth which was not adequate in terms of volume. I started learning how to swim. Realized that with swimming, too, I was having serious breathing issues. I was not able to get a proper deep breath. After many years of trying to learn by myself, I finally got to the point where I got comfortable breathing doing the breast stroke, although I do the breast stroke very badly. But nevertheless, I got to the point where I could swim for 1 kilometer without touching the walls or floor of the pool. This I feel was REALLY helpful for my stutter because it was ONE HOUR of CONTINUOUS DEEP BREATHING (through my mouth obviously) that helped relieve the tightness from my chest that I would feel when stuttering. After years of failing, finally being able to breathe naturally and effortlessly in a swimming pool was a huge accomplishment from a breathing perspective, which I feel had a positive effect on my stutter. I also tried briefly breathing through only my nose while running, taping my mouth shut while sleeping, yoga pranayama, etc. In short, Google breathing through your nose and try any and all methods to switch over to nose breathing. Nowadays I no longer have a tight feeling in my chest when I talk, and I don’t feel like I need to stop for air when talking. Poor breathing skills was definitely one factor that played into my stutter, and therefore something that I would definitely suggest improving. Having said that, it’s not the only factor so don’t expect it to fix everything. If you have any questions, feel free to DM me.