SOLVED GUYS!

it was the power steering pressure sensor switch - the wire was split inside the plug, so i re-wired it, waterproofed it, and the car is 110% perfect! the revs drop to 1000rpm when free wheeling (what it always used to do) then 900 when idle (correct idle) the revs drop so quickly when you rev it too - they don't slowly drop or hang.

when i press the clutch, the revs don't hang - they drop perfectly.

so bailes1992 - your focus has a problem! try looking at the power steering pressure sensor switch!