you have not listened to what I have said.

If it is idling too high, it is getting too much air. That is a simple fact.

And how are you trying to adjust the idle speed if you are saying it will not idle below 1000rpm ?

You say you have checked the basics.....yet also say the Bigturbo website tells you nothing ? This makes no sense. Is the "closed" throttle position where it is supposed to be ? This is an important basic first step.
Is the idle speed control valve working correctly, and is it receiving a signal ?

Are you using the correct map sensor for the chip now fitted ? And is the map sensor reading correctly ? Again, the website gives basic info here to check against.

You said it was hard to get under 4.5% CO......yet you achieved 1.4%

So was it happy at 4.5% ? you said hard to get below this...so how high actually was it ? how are you making changes to this ? Have you verified a good strong spark on all cylinders ?

And why are you trying "different fuel pressures". There will be a fixed pressure it is intended to run. I explained a specific and well known problem with the fuel pressure regulators. Have you checked for that problem ?