Hi,
    I think the problem you are experiencing is more likely melanin pigment.
Just to be sure, don't stain a section at all. Deparaffinize and hydrate, then
counterstain it, dehydrate clear & coverslip it. I think you will probably
still see this background. You could try a different color chromagen, or
bleaching the sections if this is the problem. Bleaching the sections can be
done with potassium permanganate & oxalic acid, or a concentrated peroxide
solution. Be warned however that sections love to fall off during these
procedures.
    By the way if anyone has success with bleaching WITHOUT knocking tissue off
the slides, please post your incantations, spells prayers or other tricks that
make it possible! It's hit & miss for me at this point.
Amos Brooks