Are you torqueing to specs? Usually Teflon tape is used on npt threads were the Teflon fills in the little gaps when tightened and seals. Might want to torque this badboy to specs.
It can be frustrating when crap keeps failing. I've finally made it to the point were nothing has broken in a while and I'm kinda feeling like, "maybe this is what a new car feels like"
I now drive a Japanese Ford.