Triangulated four link suspension help! Axle wrap.

[Penney86]

I am having issues with the triangulated four link suspension I built for my 63 Pontiac LeMans
On deceleration pinion wraps upward and causing a vibration. I have changed to heim joints that seems to help some. I have changed the pinion angle many times. I can get it almost to stop but if I have a second person in the car all my adjustments go out the window. It is built very similar to a mustang suspension.