The "adjuster unit" (Item Number 7 in the picture below or on attached link) on my 2002 3.0 is making a ticking noise.

It appears to be driven by a stepper motor and has ticked in the past and the stopped ticking. It appears the stepper motor is dithering back and forth as it idles.

I have removed it and cleaned it (the intake is filthy on the inside and encrusted with an unremovable yellow film which was also present on the underside of the valve cover.

Anyone experience this ticking? Should I be carrying a spare Adjuster unit. $200 part. Takes 2 seconds to replace.

Ideas? Car otherwise runs fine.