Which way are the broadheads hitting compared to the field points, to the right? (right hander) Raising brace height shortens the power stroke and works for an underspined arrow. Also where are the field points hitting in relation to a bareshaft? What kind of shaft?
CE, Are you saying the bow gained 8 pounds by increasing the draw length 1 3/4 inches, if that is true it is stacking at the longer draw. I assume your draw length is 27 or less.
I would start back with bareshafting getting the correct spine and then tuning with broadheads. Since your arrows are already cut you may have to adjust tip weight, brace height and thickness of strike plate to get it in tune. Broadheads really bring out the affects of a poorly tuned arrow.