Leak down test. That will tell you exactly what is borked. You might be able to get a loaner for autozone, or buy one for $50-100. I have the HF one and it works well.
Google leak down test and read up on what to look for. I would skip trying to figure it out with a vacuum gauge... they are only indicators of a problem... you got one, you need to figure out what end of the cylinder is the problem.
You might have a worn valve/guide, worn rings, a hole in the piston. Hard to tell without putting air in the cylinder and seeing where it comes out. With a reading that low I don't think its a head gasket... your exhaust would show smoke and after sitting your oil would have antifreeze in it.
Last edited by pfarber; 01/05/2013 4:11 PM.
