Have you also tried stretching syllables? It forces you to slow down, which allows you to alter the tempo of your speech to a more comfortable rate, and your brain will have more time to plan speech. It's been working great since I started using this technique. For example, if I need to say "Bread", I often anticipate a blockage on the "Br-". So if I focus on stretching the vowels in the word, it can trick my brain into not focusing and tensing up so much on the consonants at the front.