I think it's important for you to realize that it's not you who's doing this. You have a stutter, and that's what's going on. When a stutter happens, you're aware of it in that instance. It's not that you think it, and then cause it. It's not your fault. - Also, don't rely on models of consciousness to describe your stutter. We don't know how a stutter works, exactly, so you're running the risk of making yourself understand yourself in wrong ways. - Stutter is known to be adressable through speech therapy. You should definitely try that, if you haven't already. - Bottom line - it's unhealthy to make stutter into an active failure on your part (and thinking like that is, in fact, a type of negative conditioning in its own right). Work with professionals instead, to see what you might improve or manage better.