Vacuum leak

I know i have a vacuum leak my vents go to defrost when i accel and im getting like 15 mpg gas mileage. My problem is i dont know where to start to find the leak and fix it. Not an expert on vacuum lines what they look like or where i should look. since the vents only default to defrost when rpms are up im thinking a crack or a hose is slideing off when pressure builds which would be harder to find. Im makeing a 2200 mile trip in 3 weeks and 2 of those weeks ill be out at sea i need to get this fixed fast.
 
Well you can spray carb cleaner on vacuum lines and when the rpms change you've found your vacuum leak. Follow the small black rubber lines that come off of the intake tube, plenum to start. Spray them with carb cleaner and see what happens.