20th Jun 2012, 12:36

Brake booster. My 95 350 4x4 did the same thing yours is doing.

7th Dec 2012, 21:59

Check your brake system. Pay attention to the brake line mounted to the rear axle. It will look like it is in great shape..... but depending what you haul or if you have a load on your truck; let's say 70% of the time, that rubber hose where it crowns will rub on the undercarriage. If you are not afraid of getting dirty, get underneath your truck & look for any type of damp spots. I had a similar problem with my 1995 XLT 350 7.3 Super Crew. Just start from your booster and work your way to the rear axle. You might find a spot that looks like a rub and looks flat.