I use a propane torch (unlit of course!) at the lowest possible gas output. While the engine is running run the tip of the torch about an inch or two away from each hose. Run the entire lenght of each hose. Give extra attention to bends or hoses that rub on other parts of the engine. Take a few seconds between each hose to allow the propane to disapate from the engine area. Then repeat. Also check the intake manifold at all gaskets. If your fan blows a lot of air you may have to turn the gas up. When you find a Vacuum leak you will see a noticable change in idle. Leave all hoses attached. Make sure and test your brake booster too. These leak on occasion.

-Mike