1) Completely focus on your presentation subject. 2) Get full knowledge on the presentation so as to remove any fears regarding the subject which worsens the stutter during presentation or QA. 3) Reharse the same presentation multiple times (read out loud) 4) Engage yourself till the presentation. Don't keep yourself thinking about the stutter. This may or may not help you but give it a try. For me, if I have complete knowledge on the subject, I will stutter less compared to the one with not much.