Is my engine running lean?

     Sorry no not when I accelerate but rather when the engine begins to be 'unloaded' .. Float bowl tubes are under clip as per rotax. not aware of fuel pump vent line but fuel pressure is good. Can not find any evidence of 'false air' but i understand what you are referencing.. what I find weird is that both cyl 3 &4 plugs are identical (white) while both cyl 1 & 2 are identical but almost black. I am 'fairly' confident I have been through the electrical system in great detail.. Long story short but I moved many components from 'one side to the other' in an effort to isolate the issue.. I thought I had it down to a single coil driving the top plugs in cyl 3 & 4 but I swapped and no change. that is when I started to really question the color of the plugs from front to back. Maybe not completely related to my roughness or mag drop but it is the route I have taken.

Well this is a puzzler.  I recommended the compression check (do the differential check with the dual indicators) because a leaking valve can introduce false air and cause those plugs to be white.  I acknowledge the odds that both rear cylinders have a leaking valve is remote, but given this is a recently rebuilt engine, let’s do it and eliminate the valves as the problem. Have you called Rotec in Canada or Lockwood in the US? Both offer tech support over the phone.

I have not called yet.. I am going to wait for a cold day then swap the plugs ft to back then fly and see how they look when I land.. I will post back then

So all four plugs in the rear cylinders are running lean, that indicates a single ignition module is not likely the culprit.  If the cylinder compressions are good, consider moving the needle clips from position 3 to enrich the mixture, ground run, test fly for 30 minutes or so in the pattern, shut down and inspect all the plugs. Perhaps your front plugs should be black, not almost black.  Although my clips are set on position 3, my 2018 engine with less than 70 hours total time has always had black, mildly sooty front cylinder plugs, and barely black, almost normal-looking rear plugs from the first flight to this day. That’s not uncommon for our carburetor-fed Rotax engines. I did notice you are running the older NKG plugs, mine came with the newer plugs.