Ive got a saff cossie 4x4 and the engine has been idling crap for a few months now.It normaly idles at over 1000 rpm.When i disconnect the idle speed contorl valve it idles at about 7.50/8.50rpm.I know the revs will drop when the iscv is unplugged.Does the base idle need setting up.Sometimes when i im warming my car up on a morning before i go to work the revs go up and down a few times every now and then.Do i have a faulty iscv.Ive cleaned the valve out many a time too and lubed.Any help would be great people.

 

Change the plenum chamber gasket, the 2 O rings on the ISCV (soak it in carb cleaner while its out) change the throttle body gasket and tighten up or replace all the black vacuum hose elbows on the plenum chamber and it will run as sweet as a new born baby, believe me I've been there

 

It's certainly worth a clean, but I would also check the co when hot, as a lean mix will also cause this, it could be caused by an air leak but would have expected this all the time.
When up to temp and no load electrical on(other than engine running) there should be no difference disconnecting the iscv, as it can only raise the rpm not lower it beyond the base setting which is too low by the sounds of it, around 950 with valve disconnected is about right, when the valve is replugged back in it will raise for a few seconds then settle.
tabetha