2000 Montana

Our montana I think has California emissions on it, there's a part that recently broke and no repair shops in our area are able to identify this item. Other friend of ours with montanas of the same year cars don't have this part on them either. It's a small round "thing" located up front directly in front of the valve cover. It has a metal flex tube that bolts to the bottom and then runs into the manifold. Also has a small vacuum line attaching to a plastic nipple on top of it, and a lorger rubber tibe running out the side. It ran horribly, bucking continously, I took this mystery part off only to see that inside it is a small metal plate that apparently broke loose from a mounting place. After taking this "thing" off completely it runs great, sounds loud but won't pass inspection. There's no pics or reference to it in the repair manual.