I get this light tapping/knocking during low rpm decel or coast, but not idle. It's when car's warmed up, but has been parked for say 10 minutes, then noise can be heard for the first 5 minutes after startup. When coasting to a stop with throttle closed and rpm at 1K before it drops to idle rpm, you can hear it. If it's piston noise, will just have to ignore it I guess, but could it be lifter noise? Anyone else have this noise? Wondering if this could be caused by a collapsed or leaky lifter?