I also mispronounce. But words with a missing letter, making one letter sound like another one and so on. For me it's as if my tongue and mouth muscles are a bit lazy or numb if I speak too fast, which is something I end up doing sometimes. I end up saying 'cahn I have a glaus of waher' instead of 'Can I have a glass of water'. Could be my mouth muscles are not used to talking much I guess.