First and foremost, I LOVE your selection of exercises. The only thing that I personally would change is for you to do Squats, DEADLIFTS, bench presses, military presses, and pull ups. (You may ask me if you want to know why I think so.)
You said you do those three times a week. The set-and-rep scheme is that of a beginner (which I assume you are, at least for three months TOPS if you train properly on a consistent basis.).
Are you over training? The short answer is no, IF you are trying for a personal best once a week. For example, if your training schedule is Monday, Wednesday, and Friday, you must try for a personal best (such as a heavier weight for your 4 sets of 8 reps) on MONDAYS ONLY.
One of the best programs for you right now is Mark Rippetoe's, Heavy-Light-Medium program. http://www.startingstrength.net/workouts/
Once you get done with that, talk to me.
EDIT: Also, please keep in mind that your training schedule for a three-day a week program should be either Mondays/Wednesdays/Fridays, Tuesdays/Thursdays/Saturdays, or Sundays/Tuesdays/Wednesdays. NO EXCEPTIONS.