I finally had time to do another flow test. I parked the plane on a steep hill and got over 30GPH. I then inspected for induction leaks, none found.

I did a flight test with full fuel and had the same issue.

I am at a loss here. The marvel carb has the biggest jet it can have.

I called the factory to see if any of their aircraft had this issue and got zero help.

As long as I do not fly with aggressive climbs over a minute or 2 I am fine.

Maybe this is all from the highly modified induction system that may just cause gremlins is some CC340 engines, I have no idea.