i remember the day i developed TMJ. i was stuttering long before then, and the TMJ was caused by blunt force trauma to my lower jaw. the click or pop is it that hinge of your jaw unseating and reseating in its place. i never articulate so violently that my lower jaw clicks out of joint. not even before TMJ. it's always when i yawn or eat or bite into large things. massaging the joints to relax the jaw might secondarily help a stutter, inasmuch as relaxing your jaw any other way might help. mine seems to not have much to do with TMJ. i don't move my lower jaw that much when i speak. my stutter (blocking psychological type) is tension in my throat and chest.