95 blazer brakes stiff

Check your brake fluid and bleed the brakes.

I have been threw all the main simple stuff , fluid is fine it's been flushed and replaced within the past two months and all wheels are blead.

Large vacuumed hose from intake has hole is off is plugged or power brake unit is bad

John thank you for your response it is greatly appreciated for the help I was beginning to wonder if I was ever going to get an answer from anyone so therefore I want to start off by saying thank you okay I want to pinpoint the problem before I go and spend a hundred plus dollars on the new brake booster because that is what everyone is pointing towards that I asked not everyone but most is leaning towards the brake booster is bad okay how do I tell if it's definitely the brake booster you're saying that it's the large hose going from the intake to the booster has a hole in it but how am I going to be able to tell exactly what the problem is maybe I can describe a little bit more of the problem in detail and this will give everyone a better idea. -okay so from the time that I crank the vehicle until the time I turn it off every time I so much as touch the brake pedal it starts this loud air hissing noise and I have no brakes hardly at all and the pedal is very stiff as in I have to literally put almost all my pressure on the pedal to come to a complete stop and if I have to come to a fairly fast stop one of the wheels will end up locking down until I let off the pedal. Is there any questions out there that anybody can ask me to help with finding the problem and detail thanks in advance John and everyone else please help.

Another couple things that has been done to maybe help with some details on figuring out the problem are a few days before this issue I checked my brake fluid and it seemed a little low there is a minimum line but there is not a feline so I filled the brake fluid pretty much to the top the rubber cap that you put on before the hard cat was perfectly fine after doing so I put the lid back on and went on my way the brakes seems fine I had to come to a very fast stop at a red light a day later and after that the brakes seemed a little weird so I checked the fluid again when I remove the hard cap the soft rubber cap was wrinkled up like it had been very hot from hot brake fluid since then it's been hard to get on and sometimes when I would take the hard cap off the soft cap would be pulled down into the fluid I went by the parts store and ask them what was wrong and he said that it was too full so I removed some of the fluid through the cap back on and shortly thereafter even the same day is when I developed the hard brake pedal air hissing situation and again what is happening is anytime I put any amount of pressure on the pedal it automatically starts making a loud air noise constantly when I have my foot on the pedal and stops the air noise as soon as I remove myself from the pedal not to mention that to stop I literally have to put all my weight on the pedal to stop someone please help me figure out what is wrong with my brakes is it the brake booster and my leaking air somewhere that I have too much fluid not enough fluids what's going on someone please please please help