Update. Bought a vacuum gauge, figured it would come in handy anyways. Hooked it up and at idle 800rpm, reading was 13, increased idle to 1500 rpm and reading was 18. Is this within a reasonable range? My metal tubing from the manifold is 3/16" diameter. The thing is, today I drove it for about 45 minutes and it was shifting nicely as it has been for the last year up until a couple of weeks ago, and even when it doesn't shift at the appropriate time when I take off from a stop, it is not doing this all the time. Should I be worried and continue with some other tests? I was going to put an auxiliary trans cooler on now that I am reading more and more about tranny's, as heat is a killer. I tried to feel each cooling line to determine which one is the hot one, but cannot really feel the difference between either one. If I had to guess I would say the hot one is the one near the oil pan, and the cold one is at the back, sound right?