From your post, it sounds like intelligence isn't the problem, but rather one of motivation. While doing well academically does require a baseline intelligence, the more important thing (like most things in life) is a matter of effort. Perhaps this comes from your lack of any concrete goals.
I found myself similarly lost when I first started my university education. Actually, I started off by going to a community college, and while at first that was disappointing, it also gave me the chance to sample a wide variety of subjects, and eventually finding out CS was what I was passionate about. By finding my passion, I was able to overcome my previous motivation problems. Perhaps if you try new things as well, you might find something that sparks your drive.