Sounds like my brain. Do you have ADHD? The last example sounds like [cluttering](https://en.wikipedia.org/wiki/Cluttering), which often coexists with stuttering (I am one of the lucky people who got the two for one deal) Anti-depressives and proper sleep (thanks to ADHD meds) helped me a lot, also a breath while signaling that you're having a think can help aligning the thoughts. For public speaking and teaching, focusing on the diaphragm and breathing, and being prepared (just a few choice sentences) is the way. Tongue twisters to a metronome set at ~50bpm is also good