Everyone has choked more than once.Anyone who says they haven't are lying. No aim system will cure choking,but puts a good plug in for them i guess. I know people who play par golf for a couple of dollars a hole and can't break 80 when betting more.These same people are good five dollar pool players,but can't beat anyone betting twenty. If you haven't always choked on 9 ball shots,i would say you just have a lack of confidence at the moment. Missing several can do that. I would think you can play yourself out of it.You might try playing better/ closer shape on the nine. I think as others stated it can also help to play shape on a ghost ball while shooting the 9 as long as you still hit the cueball where you have the most confidence to make the ball.