First off, the brake pedal makes a hiss sound similar to exhaling really loud. It was like that when I got my fox 3 months ago. However, it didn't take too much pressure on the pedal before the brakes started working. Just today after driving on the interstate the brakes feel like they are completely shot. It makes an even louder hiss sound and it has to hit the floor before it even starts to slow down. It scared me to death when it first started on an exit ramp. I went to the nearest autozone and popped the hood to check the master cylinder. It was lower than the Min so I went inside and got some Prestone Dot 3 brake fluid to top it off. That being done, it still has the same issue. I pumped the brakes for a minute or two and checked the master cylinder again but it was full. So I went about my daily business knowing my brakes were bad and drove far enough back that I wouldn't rear end anyone. What could be the cause of this happening? I replaced the brake pads and shoes when I first got my fox. I'm getting my brake lines bled and my front struts put on this Wednesday. Can't do them myself because I don't have a garage and it's colder than Antarctica lol. I need to know what I might need so I can get it all done this Wednesday. Thanks in advanced!