The intake gaskets are the VX engine's achilles heel. When replacing they are composed of a sandwhich type material with very brittle outer surfaces. Hand tighten down to only 13lbs torque. You can check to see if they are malfunctioning by simply spraying the outer edges of thesegaskets with carb cleaner to to see if the idle goes up while running. If the idle changes, the gasket is leaking and you will get CEL codes. (Typically, 171 and 172, if my memory serves me right.)