1989 Accord DXcarburetor

THe Rpms in my car have started to go up and down when it is cold ever since the outside temperatures dropped down. A mechanic told me that the fast idle valve is what the problem is, so I bought it and decided to replace it myslef, but I can't find it or the one that I bought does not match anything that I see under the hood. Where is it?
I checked the repair manual, but it does not mention it. It only shows the fast unloader that is next to the throttle housing, but my valve does not resemble that.

Help please!!!