Bob_Ham.... "Time to get a helicoil or similar thread-repair product. Bummer man. To your original issue, I'm guessing something wrong with the TB, too. Mine had some 'learning curve' issues, but never like you're describing."
I searched the forum for "stripped", "stripped out"...didn't find anything to help me. Since I have no professional training in mechanical repairs, I solicited advice from two of my brothers, one a technician for refrigeration systems for an ice cream plant, the other an electrical technician. Heli coil seems to be the way to go.
I still haven't answered the question; air leak or bad TB...