I wanted to apply to BU, Northeastern, RPI, and Lehigh University.
When I got back my awful AP scores, all of which were 3’s (Calc AB, Microeconomics, Chemistry), I realized that my slim chances of getting into these schools are now minimum. I dont have a stellar GPA (3.5 UW) and my extracurriculars are decent. I did not even do that poorly in these classes and when I took practice tests, I got 4s. I am so depressed right now. Seeing all these 3’s, the admissions officers will now think I am so stupid. So much for challenging myself with a rigorous courseload 
If you aren’t happy with your scores you don’t have to report them. They are more interested in your grades in the class and that you took the most rigorous classes your school offers and looks like you did. Challenging yourself looks a lot better than taking the easy road.
I agree with what was said above. The grades in the class matter more than the actual score (and a 3 is passing, so it’s not necessarily a bad score). Nowadays, AP scores are mostly used for getting college credit after you’re admitted.
No. You’re not stupid. Don’t let anyone tell you otherwise.