If you have a scan tool that shows fuel trims, it is easy to eliminate most, if not all of the vac lines / fittings as the problem. Remove large vac from line from intake to vac tree and plug line or nipple on intake. Start engine and watch fuel trims to see if they head from high positive toward zero. If they do, leak is in vac lines / fittings. If they stay high positive, likely intake gasket leak, throttle body gasket leak, etc (something on the engine). DO NOT drive the car with no vac to vac tree, as you will not have power brakes!!!!!