Thanks guys for your responses. I haven't been out to test fly since my last posting.
But in regards to wing incidence, up or down thrust angle, or elevator trim position, would any of these cause the plane to lose altitude when right side up AND lose altitude when inverted??? Again, the plane loses altitude when right side up or inverted, even from mid to full throttle. Also, varying the throttle does not change the pitch in this range. Can this really be caused by anything but CG, other than replacing all the balsa in the plane with lead?