Brakes Failed problems of the 2000 Jeep Grand Cherokee

Total brake failure. Pedal went to floor. Had to pump to get brakes to apply. Fluid level normal. Intermittent problem.

Brakes keep failing. Shortly after purchasing the car in 1999 I returned to the dealer complaining about heavy brake pulsation at 30mph. They told me they fixed it but it continued doing it. I kept going back over and over again. The last time I went back was 3 weeks ago, and they again changed the brakes with newly designed brakes which supposedly would have fixed the problem. The dealer said they wouldn't cover the back brakes b/c they had no complaints about it and that I didn't need to change them. I drove away but the car still pulsates heavily as soon as I brake if I am driving over 20mph. Furthermore my car's engine broke down completely after 32000 miles or approximately 7 months ago. They told me the engine failed b/c I didn't change the oil for 10,000 miles. The mechanics report stated that there was water in the fuel, but they still told me it was my fault for not changing the oil. I was out of warranty b/c more than 36 months had gone by from the date of purchase. Chrysler agreed to substitute the engine and I had to pay $800. I don't understand how a new car, driven for such little mileage (now only 35,000 miles after almost 4 years) can have all these mechanical problems. I believe the breaks are faulty and am not sure how to further deal with the problem. The car dealer keeps telling me it's perfectly safe to drive.

While driving and without warning the brakes failed and caused extended stopping distance. .

Service brake failure. When vechicle exceeds speeds of 50 mph the brakes squeak, and the pedal vibrates. This occurs every 12,000. Dealership installed/used a caliber kit, but the problem still exists.