2000 Dodge Stratus Car is shaking when it idles

Our dodge stratus has been idling rough. I had auto parts store put a diagnosic tool on the computer and the code P0601 internal control module, memory checksum error displayed. They were unable to determine what it meant. The car runs well while driving and there are no problems with performance. I can only notice the car shaking while it is idling. Its kind of annoying bouncing up and down while sitting at a light.
Any idea what is causing this problem.