I don’t stutter whenever I am imitating (doing an impression of) someone. Figured it out when I was having a bad stutter day and was good-naturedly making fun of a friend of mine who did something stupid. “Hey, I’m bill and I like to down an entire bottle of jack before going out so my friends have to take care of me all night.” Didn’t have one issue. After a lot of practice, if I have time to focus I can speak very well by just imagining I am doing an impression of someone (just someone who sounds very much like how I sound).