you may need new hinge bushings, very cheap. but theres a little bit of play between and the door, you really jsut have to mess around withthem. unloosed the bolts on the door. try them in different positions. etc
as max said, check bushing first..then loosen hinge bolts on door and/or body just enough that you can adjust door with a little bit of muscle, but snug enough to kind of hold. get it to where the door closes nicely and crank em tight.
You may also have to move the door striker too once the door fits properly, or you may find it was in the right place all along. You should also make sure that when the door closes the locking mechanism engages all the way for a tight fit---there are actually 2 positions for the locking mechanism. If the striker is in the wrong position (too far away), the door won't close snuggly and will rattle etc. Ask me how I know.