I struggle with verbal expression at times (this can cross over into written expression, but the ability to review, cross out, transpose, add, and otherwise edit text before presenting it mitigates the negative impacts by allowing problems to be edited out before the text is presented to others).
I find I have trouble with prosody (speed, diction, placement of pauses) especially when stressed, nervous, over-stimulated, overwhelmed, discussing things I have a strong emotional reaction to, etc.
I also have trouble with word ordering, word substitution (sometimes one-off, sometimes persistent [for instance a couple of months ago every time I wanted to say cucumber, I said capsicum and when I wanted to say capsicum, cucumber came out instead; this occurred even when I paused before uttering the word and deliberately thought about it first, it persisted for a number of weeks]), and going blank on a particular word I need.
It's very frustrating and also impacts negatively on credibility.