I think your leak has to be right at the intake manifold. If I recall correctly the vacuum line runs over the top of the oil filter cap. If you lightly pull on the individual lines I'm guessing you may notice that the rubber hose connection to the hard plastic line has pulled loose. I've seen this before after people visit the quicky lube joint and get the guy that was flipping burgers last week but now is a mechanic.
Good luck!