It definitely feels like the adrenaline temporarily improves or even halts stuttering entirely. I’m a severe stutterer and I experience the same thing— whenever I’m extremely angry, upset, or disgusted, my stuttering momentarily improves drastically. It’s the same improvement whether it’s an anger-inducing situation or when my anger is directed at the other person themselves (i.e. when I really hate and am disgusted by the other person). I guess this is why the only people I don’t stutter around are my abusive parents. I wish there was more research behind the mechanisms for this.