I know the feeling, bro. It is horrible, sorry for thatt. I've developed a strategic way to make myself less nervous during presentations. Before I even start the presentation, I just let them know: "if out of nowhere you catch me remixing, DJing, or beatboxing, it's totally normal for me — I'm just a stutterer, so bear with me, shall we?!". I try to be funny about it, so people can be more chill when I bring it up. Reduces the stress I put on myself. Usually works for me.