AP test score vs School GPA

A university being private is no guarantee that it cares (or has the resources to care) about students in the way that you want.

http://talk.collegeconfidential.com/parents-forum/1854265-are-at-risk-students-bunnies-to-be-drowned-p1.html

Of course, any university will be an environment require more student self-motivation and time management than high school.