912 uls VIBRATION

Question for Roger Lee and others.

I have a 2016 100 hp 912ULS with 480 hrs TT.  I bought the plane recently and found there is a significant vibration in the 4000 RPM range + or - 200 RPM.

Engine has a new E-Prop that is supposedly pre-balanced at the mfg. It appears to be installed correctly with the color coded blades, engine spacer and prop spinner in the proper orientation.  There is a weight inside the prop spinner.

New plug wires.  All plugs less than 100 hrs and all 8 plug insulators appear a light chocolate brown.

Grounds for the Ignitions that are attached to the intake manifold have been removed and cleaned

Engine starts easily and idles very smooth

Air cleaners cleaned and re-oiled

New floats installed within last 60 hrs

Carbs balanced within last 60 hrs

Any Suggestions would be appreciated.