A PCV related problem I have also found (that adds to the vibration/poor idle) follow the PCV line where it passes under the thermostat housing over to the intake side of the engine. It will go back into a 1 1/2 foot of rubber hose that connects to the intake mani. I found my line to have a flat spot and allowing no draw.
The other thing I did was the motor mounts. Front and rear, I didn't do the sides. A good way to double check them is pop the hood watch the engine and put it into drive, the engine shouldn't move too much.
