I feel you, I block really bad and when I get on and off the bus, or walk into a store or some shit I always try to say hello and goodbye but sometimes it just doesn't come out. Also when introducing myself and shaking hands I usually pop out my name when we're long done shaking hands. I tend to talk a shitload in groups of people though, just gotta keep in mind that you're the person with a handicap that you can't do a thing about so it's up to them to have a bit of patience.