02 sable wagon
 

I own an 02 sable wagon. 3.0 v6 DOHC and recently I had a vacuum leak.
We noticed the sound of the vacuum leak was coming from near or under the intake manifold. Then I called my local Midas shop and they said these cars are known for their injector gasket leaks (which is located right under the manifold. So we took it apart replaced the upper intake gaskets and the injector gaskets. Started the car and it still had the leak so then we took it apart and replaced the lower intake gaskets... Now there is no other line under the manifold and that IS where the sound is coming from. Does anyone have any idea if these cars are known for their manifolds to leak because he took a look and he didn't see any cracks but it sounds like it's coming from the inside of it.

ANY help would be very appreciated!