The '98 has the individual EGR ports, one for each cylinder.
I have them shown in my '96 3.8L pictures.
They clog right at the end, where the EGR gasses enter the intake and meet the air with the PCV vapors.
For this reason, once you get to them, they are VERY easy to clean.
Try to avoid getting stuff on down into the intake manifold as much as possible.
This is a good time to check the intake for any buildup of tar, such as on the IMR plates.
To get to the EGR ports, you have to remove the upper intake manifold...which is the black nylon molded part.
There are a LOT of vaccum and electrical connections on the back side of the upper intake manifold.
The upper intake manifold gaskets are re-usable.....just be sure to clean the surfaces to remove any dirt or such that would interfere with a good seal.
You do NOT need to remove the lower intake manifold to clean the EGR ports.