Very intermitting heavy shudder stopping/starting (not warped rotors)

I'm having a really hard time looking this up because everything points me to warped rotor type brake shudder which this is not.
I am getting, very occasionally, an extreme rapid fire brake shudder when coming to a stop. It feels like a major ABS error but this truck does not have ABS so I'm pretty stumped on what could be causing it.
I thought it was a caliper locking up so I just replaced the calipers, rotors, and pads and that seemed to help a little bit but did not cure the problem. Rotors are not warped at all and no shudder during normal stopping either light or hard pressure.

I only happens maybe once or twice a day and doesn't have a pattern that I can figure out other than it's only right when stopping/starting. When it does happen it feels pretty violent.

Any advice? Would help even if I just had a better idea of what to search for so I can get past the 1000 threads about warped rotors.

 

Find an empty road and pull the parking brake handle out slowly… keep it rotated so that you can push it back in. If the vibration happens your rear drums are warped. Maybe an explanation… I am thinking that it is intermittent because your rears shoes are not adjusted and your first brake application pushes the rear shoes out partially and a second pump expands them fully and that is when you notice it, like I said, it is a theory.

 

Question.....

Does the brake pedal vibrate, or does the steering wheel shudder? If the brake pedal, see reply #1. If it's the steering wheel, check the ball joints.

 

Yr Model Engine 2wd/4wd?