Driving home this past weekend I came to a light, applied the brakes and suddenly my brake pedal went limp, falling through to the floor about 3 inches then caught, seemed like I lost vacuum boost pressure to the brake system. The brakes do work but it feels like a manual system to me, making me put more pressure to the brake pedal and the brakes not being as responsive. There are two vacuum lines coming from the vacuum boost on the firewall, one is capped off the other to the engine, both rubber lines seem good. Did the vacuum boost fail? This is one component I've never replaced since I bought the car 4 years ago. I've never changed one of these before, how difficult is it? Do I have to empty the brake reservior or can I unbolt it, move it out of the way and not have to bleed the brakes? What are the steps to the removal and installation of the vacuum boost? Any insight/tips would be helpful. What is a good replacement part? Engine is a 440/6 pack, the engine/carbs work fine no noticable difference as vacuum opens the outboard carbs. Thanks.