The supporting struts in the trunk have bad springs that lost their pushing force, and that makes the lid not pop. I knew ford had a "smart" solution like a "spring popper" but I hate to see them make money for their poor engineering or part sourcing.
My approach to get the problem is a piece of high rebound, rubber like foam cushion I found in my son's toy bin. It's about 1" thick. I cut it into shape and cut a slot on it so that I can slide it over the lock ring on the bottom of the trunk lid. when the lid is closed the cushion gets pressed, and when lock is released it'll push the lid popped. I may need to change the cushion every winter.
