I had this happen to me a couple weeks ago. Power Assist failed while backing into a parking spot. Brought it to the dealer and they replaced the brake booster. I was originally able to reproduce the problem (as it went away) and can’t anymore but I still feel like something is wrong with the brakes. When I press the brakes frequently in traffic I feel like the peddle gets higher and harder but then reverts to normal. Also, if I start the truck and then turn it off and press the brakes I have 6 depressions until the vaccume is used up. But if I start the truck, turn it off and wait 5 hours the peddle is rock hard. Sign of a leak? Anyone else have a hard brake peddle in the mornings or after the truck sits for a bit? I tried explaining this to the dealership today and I don’t think I got anywhere. Maybe it’s normal but I just don’t see it.