Get into practice man. Find patterns why do you stutter, does speaking slow will help you speak even a little. or just try different techniques. You can even go to a speech therapy. Ive had it for a long time now. But I've seen results, i can proudly say that it's not that severe like before. The same goes for you. But every man stammering is different i guess. You have to find out where you lack in. And figure out why it might be happening. And stammering is like a habit y'know. We keep doing it so brain just accept it like it's a part of it. That's why it takes time to get fix