Well I won't claim that it's fixable, but I think it can get grossly exacerbated by the stress, for instance I've had periods in my life when my stuttering was very limited, almost non-existent, while in others (especially very stressful periods) it got much more noticeable. I am on a personal quest to find out how to get it under control again. I am taking some heart from the fact that even some well-known figures including Winston Churchill and George IV were able to somehow diminish the intensity of their stutter. To all people who like me are facing this issue, please don't lose heart it's possible to make it somehow manageable, now the less optimistic part unfortunately for many of us it will require trying things on your own and seeing what helps rather than following a set script.