yup i was just gonna say thermo vaccum switch... i just had to replace this on my 88 300se as the shop that did my cylinder head broke the little tubes that stick up ..

my car actually has a diagram under the hood left of the radiator.. one of the lines goes to the charcoal and the other goes to the throttle body.. that switch operating temp is 70C.. and yes it can cause ruff idle. unhooked my idle fluctuated between approx 500rpm and 800rpm ..after installing it it ran smooth again. luckily here in cali we have quite a few junk yards ..and as my uncle always said about them places .. whatever u can fit in your pocket is free ..lol .. they actually have allot of nice chrome on the cars there .. gonna go get me a set of window chrome

just an fyi ... if you have the oart number or you can search it in partsamerica.com it usually list an option to "check what other vehicles use this part" and u can go hunting for those models ..