One thing I forgot to mention, worn piston rings can also produce a low vacuum reading, but a compression test would eliminate them!

 

Hopefully going to get some time to replace the gaskets this weekend. Not something I have done before and I was thinking about sealant. Is the small beads on the corners like what this guy does on the 3.8 basically all I need to do?

(Around about the 36-37 minute mark)

 

Yes, although a few people have recommended smearing a thin layer over the mounting surfaces on both the intake and the engine.