Still can't find vacuum leak...any help?

[dezul313]

O.K. it has been 3 days now of looking and trying to find vacuum leak. '84 300TD
Won't shut off.
Door locks don't work.
Every thing worked fine before I adjusted the valves. I've looked at every connection that I might have pull off or dislodged. I had to replace the vacuum line that goes from the back of the exhaust manifold to what looks like a diaphram near the IP. The broke because it was brittle. I could only find soft tubing to replace it with. Nobody had the hard plastic line that broke. It connects to a banjo fitting off the manifold. Could this be the problem??? If I have to buy a vacuum gauge, does it have to a mityvac? And how do you use it to test for a leak?
I'M GOING CRAZY WITH THIS...p.s. my wife says she can hear hissing inside the driver's door. I took the door panel off and everything seems fine and of course I didn't hear any hissing. Does the master door switch ever go bad? The white plastic piece with the 3 vacuum connections. It looked brand new. Thanks people...