HELP where to get this part????

I have a Frontier 2001 2.4 auto 1 1/2 cabin, I have been hearing a click, click sound everything I accelerate and it comes from this rusted metal part.
I was told that its called a vacuum switch over cylinoid [EVAT] ?? or valve assy control
Also where can I get it?
thanks for the help
http://es.tinypic.com/r/zso7q8/6