Practice with somebody non-judgemental on talking slowly so they can politely stop you to let you know that you're taking too quickly so you can try again, and whilst doing so, maintain good eye contact consistently. They can also record or time you to show you the difference. My speech therapist noticed I talk too fast as well that it's about viewing it as the slower you talk, the more control you can have over your speech. Of course in busy situations with overcrowding I personally feel the pressure to hurry up and get my words out but it really takes a few seconds at most in reality to go at it slowly.