I was watching a video of the ProPerformance guy driving the F450 for Ford 150,000 miles in 131 days. He said that the motor felt like it broke in and started breathing at or about 40,000 miles. He was on his second set of tires. Still had not changed brakes. The only days they did not drive was on service days. They were pulling a 18,000 pound 40 foot 3 axle trailer. They averaged around 1100 miles a day. So be patient and let your truck get used to you. It is just a lil' shy right now.
LAJones