Well this is ultimately the difficulty. The goal of speaking fluently is so deeply embedded that it’s not so simple to overcome. The best example I can give, is that if I said to you, speak for the next 5 minutes with a foreign accent, you cannot break character and have to fully commit to the accent. I guarantee you’d stammer less. Your intention has been moved to another task, away from fluency. Now I’m not saying you need to start to speaking with an accent. But you could try and fully commit to a particular speaking style, more passion in your voice, more emphasis on key words. Listen to someone who you admire on YouTube or tv and try and emulate how they use their voice, are they speaking fast or slow, soft or loud. Anything at all that isn’t about your ability to get the word out, but that is more about how you express that word.