I was having trouble starting my Yukon a few months ago in some really cold weather. A friend of mine came over with a can of ether to try to help me start it. He sprayed too much and we blew up my upper intake manifold. It's in several different pieces, but with that much pressure I'm concerned that something else was damaged, especially since there's a decent sized oil stain underneath of it. I'm not sure what that came from, but from what I can tell it doesn't appear to be leaking anymore. I finally got around to starting the repairs this past weekend, but I noticed some broken vacuum tubes and I'm not sure what they go to. Can anyone tell me me what they think may be causing the oil leak, and if there's a diagram online somewhere that I can take a look at to determine where the vacuum tubes go?