Cruise issues

2002 taurus bucks badly with cruise on when trying to downshift when going up steep grades

when going up hills with cruise on my 02 taurus bucks violently while trying to down shift and stay at speed. I must turn cruise off and deexcelerate to make stop. what would cause this/

I would suggest the problem is not the cruise control, but the transmission. My guess is that there is a shift solenoid or valve sticking that is causing the bucking as the transmission bumps between gears. The cruise control is making it worse, since it is holding the accelerator down when this starts happening. You or I would feel something is wrong, and lift off the gas.

First, check the transmission fluid level, and note if the fluid looks pink and fresh. If the fluid doesn’t look pink, but brown and smells burnt, it needs to be changed. Hopefully this will help, and prevent further transmission damage.