After changing the battery, and then turning the key to power but NOT starting the car, this part will click (chatter) at the relay for a few seconds. This also occurs when turning the key off (again with or without the car running). I think this is part of the EGR, but I am not sure. I do not have a shop manual, only a generic Haynes. This part is not in any pictures in this manual.

The part is mounted on top of the intake AFTER the throttle body.
It is on the inside of the the bend of the accelerator cables. The unit has a relay at a 90 degree angle and two hoses that are 90 degrees from each other it is bolted down to the housing.

I have some pictures at http://photos.yahoo.com/bobpassno02a in the album Maxima.

If someone can identify this part, and if possible let me know if the clicking at the relay is acceptable, it would be much appreciated.

 

That is your Evap Vent Control Solenoid. Or something or other. It is an Evap thing. I am sure the relay clicking is normal, even if it were busted it wouldn't prevent the car from starting. Mine went bad, car drove fine, just threw a CEL

 

It might also be the Idle Air Control Valve clicking.... Mine did that for a while....