My 05 Cummins brake pedal comes back slowly. Not a big deal unless pulling a trailer with electric brakes. I replaced the hydoboost and no change. Flushed the power steering fluid and the brake fluid - no change. While doing the brake fluid the front left seemed restricted so replaced that line - no change. Master cylinder had blow by anyway so replaced that - no change to the slow pedal return. Put new front pads on cuz they needed it - no change to the slow pedal return. Pretty sure the booster is responsible for how quickly the pedal returns, and the one I bought was a rebuild from advance. Anyone have any other ideas before I put another booster in it?