Stu/msd normally maps/writes for around 2% to 2 1/2% CO idle when hot.
Make sure you set the fuel pressure to what it should be as well, if you phone stu with the chip number written on the chip he will confirm what it is, and the settings needed for that chip.
If it really was stone cold yes it most likely would cut out unplugging the iscv.
The base idle needs setting up though, once the co has been set(fully warmed up) then disconenct the iscv, turn off all electrical loads apart from the engine, and using the screw/locknut on the underside of the throttle housing adjust to around 900 rpm, when you plug back in the iscv the revs will most likely rise for a few secs, this is normal, but will settle to base idle a few secs later.
The iscv is used to raise the revs only, when cold, when electrical loads are applied etc.
tabetha