Hey im new here, i just bought a 91 318is

and love her.
She has a rough idle though
When started from cold or hot it idles around 1000, but then the engine seems to misfire and sputter/shake then shots right back up. Ive checked the plugs, and for a vacuum leak. no leaks and the plugs are clean. from what ive read it seems like it could be the ICV ( not sure if thats the proper name)
Thanks for the imput