Did you go back with the original hinges? If you replaced the hinges with thicker ones or a different brand then their ability to swing maybe greater than the old ones. Also, did you have paint anwhere on the pins or pivot points of the old hinge, this may cause them not to swing shut as much as the new ones.
solution. Instead of a shim, pre drill a hole behind the center hinge and place a flat head screw in under the hinge..leaving the head of the screw above the surface just a hair. reinstall the rest of the screws down to the counter sink in the hinge (dont overly tighten, or use a drill). This should put enough a bind the hinges to keep the door open when you open the door.