4.0 litre Grand Cherokee Orvis Automatic 'R' reg.

Hello, I'm having a problem with the above car. the problem is mainly on
Long inclines. At about 45-50mph in 4th it starts juddering. Between
50-55mph it switches to overdrive and judders like crazy. It almost feels
like one of the front wheels is square. If you travel over 55mph in over
drive it sometimes settles down, but not entirely.

It sometimes happens on straight flat roads also, but not as often, its
mainly inclines.

Also, sometimes it cant decide which gear to be in and you put your foot
down on the accelerator/gas and it will not change down until you reach
kick-down when it drops 2 or 3 gears and sets off like a rocket!

We have been to the dealer about this and they have no idea what's wrong.
I'm hoping that someone else might have an idea or solution so I'll be ready
next time I visit the dealer (Wednesday 30th June).

I hope somebody can help!

Thanks in advance.

George H.