That seems really high, so it is likely more then one thing. Improper ignition is often the culprit. You may need to change the wires as well. Make sure you have the NGK V-Power ZFR4F-11, other plugs don't have the correct heat range.
But timing should be looked at closely.
The VX also has a different cat, it connects directly to the manifold. They are more expensive then the ones that connect further back. By now it has probably been replaced, and the replacement ones don't last as long as the OEM.
Like Trollbait said, cleaning out the EGR and the passageways in the intake, that sometimes can get clogged up is worth looking at, There is lots of info here on cleaning the intake.
Good luck, and I agree, make it run right, don't just fake it through the test.
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