The soapy water test does not work well for finding a vacuum leak since the direction of the air leak will be from outside to inside. I use a small propane plumbing torch with a plastic hose attached to the end. Open the propane valve and them run the hose outlet over any spots which might leak. If there is a leak the propane should be pulling into the engine intake and you should hear a change in engine RPM. You can also use carb cleaner instead of propane, but I find the carb cleaner to be more volatile because of the spay/mist.
