You're not alone. I faced too but also I have gone through many interviews where I have rejected the offers too. Just believe in your ability instead of limitations(Stammering is definitely not disabilities. It's just a limitation.) Perform hard and of course before starting of any interview you can say humorously that my mind is working on 5G but my speech in other hand, is still working in 2G. Stay happie:)) Feel free to dm me to discuss further.