Intermittent starting problem

I have a 2001 Chevy Blazer which has an intermittent starting problem. The vehicle will start fine (first time) for days and then all of a sudden it will not start. The engine will turn over and it almost starts. After trying to start it 5-10 times and leave it sit for 1-2 hours, it will start fine. Then after several days it will happen again. Anyone have this problem? I would be interested in knowing what fixed it. thanks.