Rough-idling 360, can't figure it out!

My D150 was having similar issues. After trouble shooting I started replacing parts........I replaced the distributor, carb, coil, ignition box, plugs, wires, fuel pump, fuel filter.....after all of that (and to my embarrassment) it was a vacuum leak that I had missed WAY back when I started trouble shooting (near the master cylinder)....before I bought all the parts :\