flygilmore , one of the things i would do is faten up the low end when you are at idle and you open the throttle . it mite be hard to exolain but i'll try
first thing you have to consider is the weight of the plane and how fast it is going when it is going down or weight and air speed
onother thing to think about is when the engine is on the ground and the throttle is opened you do not have air speed pushing on the prop so there is no resistance on the engine whats happening is the engine is or (may)
be going lean it would be like not having a prop on the engine and if you think about it the prop could over rev the engine momentarly at a low rpm
think about this if the prop was spinning freely lets say in the back up a pickup truck would the prop turn ? fast or slow most likley the same speed or possablely faster depending on the size and pitch does that help shed a little light on the subject


Jim