It does it with 2 idle control solenoids.... thats why i said 'don;t tell me its the idle control valve!' :P

idle control valve- i had to have this replaced on my 1.2 16v. cost £202 @ vauxhall fitted

Just as a side comment.....

The idel control "valve" on the 1.0 12v and my 1.2 16v is just a solenoid that opens and closes the throttle by pushing on the rocker.... its not really a valve you can clean.

You may be right about an air leak.. i will scrutinize it.. might even wrap cling film round all of it!

well if its not ya idle control valve, first thing to check, it will be an air leak, all it means is a tiny amount of air is getting into the system after the ai massmeter or throttle body and this amount of air is not gettin added into the calculations the ecu will be making so its gettin confused, so check
1.idle control valve remove and clean/replace
2.airmass/airflow meter
3.check for air leaks round inlet gaskets (spray wd40 round gaskets and watch out for a change in rpm)
4.check the inlet trunking to throttle body these can develope holes (mine did)

A while ago i had to put my airbox back on as standard so i could have the air flow mass meter changed (different problem to do with power losses).

The eratic idle was worse than ever with airbox on... a freeflowing induction kit seems to lessen it.

no induction kit just drilled air box and peformance filter..but it did this before drilling the air box...its been a lil worse recently as well :(

if ya got an induction kit, it will be that for sure, its normall, one way to check is to put the old air box back on, my engine has been fully re-built and it does it (without cold air feed)

Sorry to thread-jack here matey but mine does the same at idle.. mine's a 1.6 sport.. wot cud it be?! :|

When my Corsa B 1.2 16v is idling it wavers about allot and even gives a shake every now and then that you can clearly feel through the car.

Before any of you tell me to change my Air Flow Mass meter or my Idle Valve... i've done both.

I'm wondering if it's incorrectly gapped plugs, i changed some new ones from 0.8mm to 1.0mm as per haynes.. maybe i should have left them at 0.8.

It might also be a blockage in the fuel line.... fuel filter?

Car seems fine once you give it a bit of gas.. only a problem at idle.