"RPM variances at idle (especially in gear, running a 25P or higher prop) are quite common. Idle speed is "controlled" digitally by manipulating the ignition timing.
This will result in "some amount" of RPM hunting... although it is usually over a 25-100 RPM range. Despite the readout, you should not "perceive" that the engine is "surging"."

Thanks Don..........that was what I was looking for.........