Hello, looking for some advise. When driving my 2006 Montero uphill in a highway on 4th gear, at the time of reaching the top and shifting to 5th, it suddenly appears to change gear to 2 or 1, or like it activates 4L, and drastically reduces speed to the point I need to move to the shoulder and stop. Very weird! Has anyone out there experienced something like that and know how to fix it?