Thanks to everyone for all the information. These forums are a great source of information. I just want to make sure I have it correct.
There are two behaviors that people have been discussing here. Hanging and step.
Hanging: As I understand it from reading is that the #4 version of the ignition module has a control programmed to hold the RPM up for a while when you throttle down to allow the prop to cool the engine since the ambient air will not cool the engine when the plane is flying slow. This can be a problem when coming in for a landing when you throttle down and the engine does not return to an idle in time before you run out of runway. This is not a problem that will cause the engine to die if it is tuned correctly. If you have the #4 ignition module you can replace it with the RCexl module which will work with most all DLE engines. The replacement is only needed if this hanging is bothering you. One question is what DLE engine models have this built in. DLE 20cc for sure but what about the DLE 30, 35, 50 55 etc.
Step: Is this the point when the timing advances. Do I understand that the timing advances fully at around 2200. And there is not really a curve. This can mean that if you advance or retard the throttle the engine can jump RPM up or down. Is this just ignition module #4 or all modules. Also only for DLE 20cc or all sizes. If tuned correctly then this is just a behavior that that will not cause the engine to die or cause any other problems.