From my limited knowledge it sounds like the
oil pan. Centrifugal force cause
oil to temporarily move away from the pump. You could either replace you pan with a Canton "race" pan or add a
oil accumulator. (Check out "Accusump" or Moroso)
I haven't heard too many great things about the performance of the low profile "cobra" pans. My engine builder promptly removed mine and replaced it with a Canton "T" sump 7 quart pan. It rides ALOT lower than the original, but I haven't hit anything with it, yet.