Where is the O2 sensor on a '98 3.8.Is it before or after the cat.Is that something that pretty easy to change yourself??? Does anyone have any links with pics i could use to change mine???

 

98s are OBD2 right? If so then they should have a second 02 sensor after the cat

 

Yup, one before and after the cat.

 

Actually, there are 2 before the cat and 1 after.

 

On some OBD-II there are 4 sensors: 1 in each manifold, 1 before cat, and 1 after cat. Not sure what year, ('98 or '99) they went to three: 1 in each manifold and 1 after the cat. The ones by the cat are easy to swap out. The ones in the manifolds are a bit difficult to access.