In the same vein, drinking a bit of alcohol as badely as it sounds does help reduce my stuttering. Obviously making a habit of having a few beers before investor meetings or sales calls is not a viable solution.
Have you considered propanolol? It doesn't pass the blood brain barrier, and side effects are incredibly minimal. Since it sounds like stress agitates your speech, this may be a pretty good option. It's often prescribed for public speaking anxiety, but I'm sure most doctors would prescribe it for investor meetings if you asked.