Guys I desperately need your help. I have my nephews '04 Titan in my shop and we have a very loud or knocking noise coming from the top of the cylinder head on the passenger side. I pulled the valve cover and checked the valve lash, everything is within factory specs. I pulled the timing chain inspection cover on that side and it looks good, sprockets are good and the chain is tight. I've had it running with that cover off and everything is running smooth. One strange thing is if you get the RPM's up to about 300 or 400 above idle the noise stops. When you get above the 300 or 400 rpm's it comes right back. I have also had it running without the serp. belt to make sure it wasn't coming from there. I have used a screwdiver with my ear to it and it the loudest right at the intake runner on that side. I am stuck, any ideas?