Which colour for valve?
 

I really couldn't figure out how to title this, but I'll be replacing the AOS on my car this weekend, and at the same time I'll be cleaning out the throttle body, intake runners, and some of the vacuum lines. When I had everything apart last time, I mistakenly removed the brown and white valve (I am assuming it's a check valve) that attaches to the vacuum lines beneath the intake runners. Can anyone tell me which direction this valve should be installed, and if it's important enough to replace while I'm doing the AOS? It's a small unit, with what looks like a 1/8" inlet and outlet, and is half brown and half white. I'll try to snap some photos if no one can figure out my description before the weekend arrives. Thanks for the help everyone. :)

I believe you're talking about the intake distributor check valve. The factory manual lists this part as black/white (are you sure it's brn/wht?). If so, the black side fits into the rubber sleeve between the TB and the intake. The only other valve I see is the fuel venting valve and it has an electrical connector on one end - the end which is closest to the TB.

You were right. With all the grease on my hands and all over the parts, I got confused, but it is indeed white and black. Thanks for the help. I got the AOS replaced, only to find that my MAF needed cleaning also. So now that both are done, my CEL has been gone for a while now, and no plume of smoke upon startup. :)