2000 Ford Explorer A/T downshifts unexectedly

No
not if you drive it accordingly
steep hills are best negotiated in low fears with plenty of rpm applied
for example on a steep grade with a manual 1st or 2nd or possibly 3rd and the rpm around 2000 constant will cause it no harm
automatics will go to first automatically so keep the rpm at that mark
engine damage is experienced when the gear selected is too high and the engine is placed under extreme load so down shift to allow the engine to work easily
When going down hill select first and only use the brakes to maintain the 2000 rpm range and allow the engine compression to hold the car speed back
the rule of thumb for experienced drivers is this
you select the same gear to go down that it took to come up

Yea! I'd like to see the answer to this also!
My Ford Explorer 2000 does the same thing going up hill. Especially with a loaded trailer on.
Local mechanic had it for the day and couldn't put his finger on it.
I can alleviate the problem by turning the AUTO Trak knob to 4x4 Hi while driving and the jerking stops.
I'll keep an eye here to see what others think
Cheers
Trevor

are you serious ! 40-50 mph max , depends on the road uphill higher down hill lower gear don't put in top down a steep hill , there are lots of variations , have you learnt to drive even so i'd book some lessons

OVERDRIVE is fine in most driving. if you tow a trailler or pulling long hills take out of overdrive. otherwise the vehicle will handle when to shift.

first things first. have you identified whether or not it is using a kick down cable? if it is, chances are this is your issue. if the colar breaks or the cable gets freyed and sticks inside the sheath, it will cause definate shift issues. let me know

Go to auto zone to check for code it is fee.

I had a similiar problem on my 1999 Dodge Ram 1500 Conversion Van. It ended up being a partial collapse of the catalytic converter which didn't allow adequate exhaust. The problem only showed itself because I could not get over 55 mph going up a small hill.

try changing the tranny oil and pan filter

its just time for a tune up
what your getting at low RPMs is just a misfire. i would bet to say that you engine light is also on.
so plugs and clean your throttle body and if you haven yet replace your fuel filter.
later paul

All Toyota auto trans cars downshift when descending a hill when you tap the brake. This is called "Downhill Shift Logic"; what this is for is to eliminate the double shift when you come to the bottom of a hill and then accelerate. Normal condition. Usually happens above 38 MPH.
Also: The cruise will accelerate when going uphill. Normal condition.Plus: The cruise will not disengage back to the set MPH after you top the hill. Toyota recommends to disengage the cruise when encountering steep terrain.