Why is my montero shifting so roughly when it shifts down going up hills?

When this happens does your neutral light come on and starts flashing? And it seems to stay on second, or whatever gear? I have a 2001 Mitsubishi Montero sport, brought it to a dealer for the same problem and that was shift solenoid D. Its called the under drive solenoid. When the solenoid fails it will go into "limp mode" which means it stays in one gear. Don't know if that helps but just a general idea. Getback to me and maybe i can help you out more.