Arg, my S2 wont idle properly.

It used to idle fine when starting on cold, but a few minutes of touching the throttle (to reverse out of the drive) the revs would drop to around 400-ish and stay that way until the engine had started to warm up.

So I sat the car on the drive, rev'd it slightly and waited for the revs to drop before adjusting the revs so that it was comfortable.
Started the car up in the evening (from cold) and it was idling fine.
... but now when its warm/hot (good running temp) it idles between 1000 and 1400 rpm

I had a quick look through the newest Fast Ford before coming on here, and read that their staff S2 has had almost the exact same problems as I have had so far with mine.
With their idle problems, I think it came down to the chip on the ECU.
I also read in a previous Fast Ford that the ECU I have in my S2 can cause running issues.

Could swapping the ECU be the answer ?

CheeRS