cruise control is very weak
Cruise control will hold at 65mph on fairly level ground but when a average incline is extended for about 2miles as on a long stretch of highway, it will slowly loose speed, about 8-10 mph untill the road flattens out again. You can feel the cruise control trying to work but is very weak. Is it the computer or maybe the vacume plunger or something else. How do I check it.