It's in the throttle body,

if you're not experienced on backprobing computer control wires, and don't
at the very least have a 10 megohm input, digital volt meter.

I would say don't bother asking for the diagram, nor the testing procedure,
you'll do major damage.

I can tell you. These valves and the throttle body area where they seat and
air passages they manage get quite filthy.

Before you do anything, pop the plastic hose from the rubber snorkle hose
that goes to the air filter, and look for antifreeze. Then you have a horse
of a different color, especially if it looks like a grayish black mayonaise.

I hope this helps?

Refinish King

Hey Stangdude...  I am still working on mine as well..
HOPEFULLY, I will get the catalytic converter, muffler
and tailpipes replaced this week..  I have gotten an
intermittent error code for the oxygen sensor twice since
we last emailed (about 4 weeks ago)...  That will be
next I guess...