So you got new lifters or what? My 04 is making that sound, especially when colder and /or excellerating. I thought it was media rattling in the cats since im getting cat codes.Havent found anything touching moving parts under the hood or truck. My motor just got installed a couple weeks ago. I seafoamed and modded the intake and truck runs, idles, smooth. good gas milage. this noise drivin me crazy. Was it the timing for you or valve adjustment? I dont see your post of how you fixed it, just that it (the valves) worked themselves out.