It looks like this
http://snipurl.com/xoxp

It should be on the front of the engine mounted almost horizontal right
between the heads. Pointed toward the water outlet. It is easy to pull
of without removing anything else. Except the electrical connector for
the water temp sensor and the connector on the EGR. Remove the bolts,
pull it out of the intake, rotate it so the flange is 90 degrees from
install position then pull it out the front and then tilt the top up.

Pull it and clean the pintle of the carbon chunks. Once clean take a
piece of stiff wire and run it into the port and break loose as much of
the carbon as you can. If you want to stop this problem there are two
ways. ONE is to manually remove all the carbon by pulling the engine
apart and scraping it out. TWO is to grab a can of GM top cylinder
cleaner, follow the directions on the can.
One warning DON'T USE IT INDOORS.
The other warning don't allow the exhaust outlet to point at ANYTHING
you value since there is going to be a LOT of carbon and crud coming out
that pipe. It will make you think the entire car is burning up when you
see the smoke it creates.
Once the treatment is done. Pull the EGR and clean it good, then install
a Kleen Screen gasket instead of the normal one. It has a built in
stainless screen that stops any loose carbon from getting into the valve.
This also cleans out any carbon in the cylinders and will free up some
of the crap in the rings as well. Because of that I also change out the
oil and filter at least once after I use it, it is usually VERY black.