You say; "When it gets to the g84 line it starts to feed but for the first second it feeds, the carriage acts funny, the whole carriage starts to shake."
Does it then smooth out? I have tapped same size with a TL without any problems.
One thing I did notice with my TL1 was that the carriage would shudder a bit whenever it started moving quickly and this went away when I removed the handwheel. The handwheel runs on a rack and has clearance and would slop back and forth whenever the carriage started or stopped.