On my E-420, occasionally when I am at a stop light I hear a loud whirring/chattering sound from under the hood. I was finally able to diagnose the part that is producing this sound. The part looks like a sensor and has a socket on top into which an electric connector plugs in. It says "MOT" on top of the part and it has two tubes coming out from either side. It is located on the driver side and under normal conditions it gives a pulsating vibration when you touch it. Can anyone tell me what this part is called so that I can replace it? Thanks.

Called a regeneration valve (or purge valve).
With the hood up it sounds like a ticking lifter when operating but is normally not noticeable with hood down.
It brings gas fumes from the charcoal canister into the engine to be burned.

Thanks Rick76.
I googled the Regeneration Valve and found forums which also mentioned the flashing fuel indicator lamp that I have seeing in my car for quite some time. Hopefully replacing the Regeneration valve will fix both my problems.