Truck has 68000 miles. Just noticed this morning. While pulling out of the driveway there was a rattle. Then at 30 mph and 60 mph same rattle but also at different speeds. If i let off the gas or sped up the rattle will go away temporarily. Not sure what the problem is. I crawled up under the truck and everything looks normal. I opened the engine bay and nothing out of the normal except that the vents by the windshield had a lot of leaves in them which I removed. Any help would greatly asperated.