Hi All, I'm new to this forum and am hoping you can help me with the below mysterious problem that nobody seems to be able to understand or solve.

2008 G35S Approx: 130,000 Miles
Vehicle Knocking sound coming from the driver side dash or engine firewall or engine.

WHEN VEHICLE IS NOT MOVING:
1. There are no Knocking sound coming from the Driver side Dash or engine firewall at any Engine RPM.
WHEN VEHICLE IS MOVING:
1. In !st gear, With the Vehicle moving, the Knocking sound coming from the Driver side Dash or engine firewall will start at about 2900-3000RPM and up and will countinue until the engine RPM drops below 2900-3000 RPM.
2. In 2nd gear and any other gear, the above condition exists.
3. During shifting from one gear to another where the RPM drops below the 2900-3000 RPM range, the knocking sound stops until the RPM reaches 2900-3000 RPM.
4. While the Vehicle is moving in any gear, the knowing sound will go away when the RPM drops below 2900-3000 RPM and starts again when the RPM reaches 2900-3000.

Thank you much!