I sometimes do. For stuttering, I usually do it more when I'm nervous. As for the lisp, if I speak too quickly then it starts to show. To give you an example... Normal pace, watching my words: "It is possible for me to speak correctly". When I get into what I'm saying and fasten my speech: "It is poshible for me to spleak correctly". "P" and "S" sounds typically trip me up when speaking quickly. There are certain words that I tend to slow down my speech for (or avoid and choose to use another word instead) and carefully sound out, in order to avoid particular errors. However, if I'm getting into the swing of a conversation then I tend to forget to watch my words and start to lisp more. Sometimes people tease me for this, but only in a jestful manner. I'm not as bad as I was before I went through speech therapy, but every so often my lisp and my stuttering show themselves.