I tap my forefinger to my thumb for each syllable. It helps to slow me down. A lot of my problem was that I spoke too softly, so I am trying to speak louder and slower. In a business setting, I try to tap my foot to each word, so it is not as obvious. I also before I speak I exhale a breath then speak, that helps especially at the start of the conversation. If it is something really important, I write down what I am going to say. So I am just focused on my speech and not trying to string together coherent sentences on the spot. Let me know if you try these and they work for you or not?