[dcw]

Sorry for the slow response - only just seen this!

You might have fixed this, of course, by now. But if not...I don't know the B18u engines I am afraid - 480s are my thing - but 223 is the idle control signal...

I suspect that someone drilling holes in the pipework was an attempt to bodge a fix. It can't really be helping!

First things first, try and seal up that pipe - ideally replace it. Then I'd check the throttle position sensor - if it's at all like the 480 ones oil gets in and upsets that signal. Clean it well.

I'd also check the basics like the distributor cap and rotor arm, plus is the throttle valve flap clean?

After that I'd start wondering about the ECU...

Let us know how you get on with this.

David