Okay, I had a similar problem to this, when my car wasn't mine. If you give me some time, I'll ask my dad and find out what ended up being the problem. I think it has something to do with the computer, ICM, the belt, and the timing chain, but not really sure until over Thanksgiving, when I'll be able to talk to my dad. Let me guess, you get it started in the morning, go to work/school, go to start it again, and it won't turn over. After maybe an hour of continually trying to start it, it might start up, but not always. Has left you stranded in parking lots during the day, and sometimes at night.
At the moment, and I'm not entirely sure why it does this, but try spraying some belt dressing on the belt when it won't start. Sometimes that did the trick for us, and sometimes it didn't.