Ford Expedition Shudder

The “experts” can’t seem to figure this out.
I have a 199 Ford Expedition that started shuddering several months ago. The shudder was the most pronounced when braking, but was also pretty bad when accelerating and letting off the accelerator.
I took it to a Nationally recognized service center. They charged me over $1,200 to replace everything associated with my brakes, but the shudder, (although no longer so pronounced when braking), was still there.
Their best guess was the “U” joints, but since they had just a little play in them, they weren’t sure that that would cause so much shudder.
I took it to a Ford dealer. They had it for 3 days, and charged me $366 for a diagnosis that I had 3 different brand name tires, and the All Wheel Drive was having difficulty keeping the wheels in sync.
The problem seems to be most pronounced when letting up on the accelerator Also pronounced when accelerating, not as much so as when letting off the accelerator, but when cruising steadily with my foot on the accelerator, it nearly goes away.

Please Help!

All wheel drive and even slightly different size (wear) can cause the exact problem you are having and can cause damage.

I am guessing the dealer was right.  Get four matched (wear, make, model etc.)

If possible to put vehicle in 2wd try that first and see if it disappears.

Did you replace a tire(s) and it started?