ok guys who have been playing along. this is the conclusion ive come to.
Well guys, after 3 days straight trying different things, i still couldn't get the car to run right. I still dont get what went wrong, what started all this and caused these problems, when I had it running fine until June.
Anyway, i know it was directly related to the ISC valve, and today in trying every possible solution, I tried plugging in the original XF unit. which generally speaking it should not work, and doesn't work properly with EL injection.
Well, the original XF unit, is by far giving the best result. So i have plugged it back in, and put the original pipes back in, and took it for a drive, it seems happy. Granted, it was tested at full running temperature. So tomorrow morning, when its bone cold, I will fire it up and see how it goes on cold start with the XF ISC valve.
It isn't 100% with the XF ISC, but its definitely bearable.
What it's doing is, it holds the idle at around 900-1000rpm for a couple seconds before settling down to normal idle. but it is consistent. it drives really well, fine changing gears etc. but the idle hold before resting is something i guess ill just get used to.
I still intend to get my brother to CNC cut a solid billet alloy block to mount the E series ISC to, and test it again with a much better built mounting block, and go from there. but at this stage, the XF unit with EL injection seems ot be the best result.