You may have a warped manifold, which would cause a vacuum leak. Remove the manifold and put a straight edge, like a carpenter's square against it and look for a gap. If the gap is less than 1/8 inch, you may solve the problem by using a Remflex gasket. This is more expensive than the stock gasket ($50 vs $10) but it is thicker, 100% graphite and crushable to an extent. It is supposed to cover a gap up to 1/8 inch. Otherwise find another manifold or have yours milled flat by a machine shop.
Kent
