P-Diddy.

Take a very close look at your elevators, what you are describing is either the elevators are not moving the exact same distance or you are too nose heavy

How I check my CG is pull up into a true 45 degree climb at 80% or more power, roll inverted and take you fingers off the sticks.

If the plane does a very slow arc back towards the ground then you are slightly nose heavy, if it continues in a straight 45 degree climb you are neutral, if it starts pulling towards the gear (remember you are inverted) then you are tail heavy. I always start with the CG set by the book and adjust to what I want to see.

On the Showtime, neutral to slightly tail heavy will work well for 3D. I go just a touch nose heavy on everything because that is what I like.

When I say nose heavy, the arc towards the ground should be very very gradual. If it arcs quickly you are way nose heavy. I have actually quit measuring the distance after the maiden flight of all my planes since I have found doing it this way sets the plane for the way the wing is. I do fly IMAC sequences and this has long been a very acceptable method of checking CG