I think it's mental thing. They need to just think of something else instead of worrying about missing the free throw. I remember one time getting fouled intentionally in a men's league game awhile back with a few seconds left and I had to make both to force overtime. I can remember someone was trashing talking so I just started talking back in between my shots and just naturally made them both. It was because my mind was not fixed on missing or making but on something else, a kind of Zen thing. I think that's what the Jazz need to practice, thinking about the last time they got laid or something like that, instead of that they might miss the shot.
Damn, I hope they are reading this. I know they have been playing professional basketball for a while, but this advice is probably eye opening if they saw it.