Ive driven my truck for a little over 5K miles. Recently Ive noticed that its pinging at around 35-40 mph when you give it gas. I know its not the gas. I use the same station for all the vehicles in my family. It also seems like its shifting all the time at the lower speeds. When I slow up at a light or stop in traffic it almost feels like the truck surges as I apply the brake. Im assuming its the transmission shifting in and out of gear. Anyone else have these kind of issues ?