really bad clicking, possible valve tap?

[Ender_Zero]

hi guys, this is a really loud clacking noise that comes from the top end (or at least i think) but i dont believe its the timing chain...it seems to only come around when at about half throttle or when trying to maintain speeds. it goes away when im on the throttle a little, and when i let off completely. it sounds alot like a valve is tapping the cylinder, but the fact that it goes away is puzzling... can anyone help?

[Ender_Zero]

went by a shop and asked them what it was, they told me the rod was coming loose. crap.

[Chezedik]

All the KADEs I have ever seen (altima included) develop a tap in the head after a few thousand miles, it is inherent in the design of the head. They use a cam on bucket design. It goes away when you rev it, but comes back at idle, I don't know about at speed. Try some lucas and be done with it. Wait, that may be premature, did they lift the engine and take off the pan at your shop.