I'm fairly confident that they're not related. To compare cases, my stutter is quite severe yet my writing is completely unaffected. The only way I really see the two things being connected is if the stutter comes from a different cause, one that also lead to this writing difficulty - I don't think that's the case judging from the information you've given. In my experience "fluffy" writing as you call it generally consists of writing the same thing in multiple ways, highlighting a different aspect each time. I hope that helps. Edit: Stuttering by itself is in no way an intellectual disability, it's a mechanical issue.