I am not sure that I have Tachyphemia, though my speech does become quite "cluttery" at times. As a child, I was often chastised for speaking too quickly and for stammering over my words. Though I've been through speech therapy and have improved my fluency, I have noticed that I still slur my words together, have unusual articulation, and sometimes speak far too rapidly for comprehension. As far as I am aware, however, I do not mix irrelevant words into my speech.
In any case, you are certainly not the only one with this disorder (just check Google: you are not alone). I wish you the best of luck in dealing with this particular sort of speech. May you find serenity and comfort.