Welcome to AF.
Sounds like a lower intake gasket leaking, typicalon the 3.1/3.4's, how many miles on this 99 GA ???
From the pics, it also looks like you are leaking oil out the LI gaskets.
Have you noticed any coolant in your oil or oil in your coolant ??
Here is a link for the LIM procedure.
3400 SFI LIM Gasket Procedure