This pretty much sums up what has improved my speech drastically. I strongly, strongly, strongly believe that slowing down when pronouncing words has helped. I always feel like my brain is trying to squeeze out the word faster than my mouth can so it causes a disruption in my speech. For example I am going to say: "The swing in that park over there is brown", I'd usually say it like "The swing in the park (breath) over there is (breath) brown". My main letters I stutter on are vowels pretty much, so taking a subtle/normal breath before the word really helps. No one notices too, a lot of people breath before saying a word.