[old_master]

You don't need a vacuum gauge for this test. Disconnect the filtered air intake for the PCV where it connects just behind the IAT sensor. With the engine at idle, there should be a slight vacuum on that line. Seal the end of the line, with your thumb, and pull the PCV valve out of the driver side rocker arm cover. There should be no vacuum at the hole in the rocker arm cover while the engine is at idle. If there is vacuum present, the intake manifold gasket is leaking internally and must be replaced.

Your oil pressure at 30-40 psi at idle and 60psi under load is great! No problem there.

Post your results.