I made a hard U turn and as soon as I straightened to stop at the light, the brakes didn't work and pedal went to the floor, but recovered fine when I pressed them again and stopped just short of hitting a car. This is why I thought I pinched a line, but I couldn't duplicate that issue. I have not checked the vacuum to the booster yet, but I thought a hard pedal was a sign of a bad booster. Fluid level was the first thing I checked and new fluid was ran through last winter. I traced the lines from the master cylinder throughout the truck; all good. I replaced rotors and pads in 2012. Repacked wheel bearings late 2013, when I rebuilt the front suspension, so almost 1 1/2 years ago. Once I get those tires off, I'm hoping to find the answer. I'm just trying to cover all my bases before I start tearing into this thing, because I always get a surprise. My lot in life.