A mate just bought a '90 saff, As far as I can make out its has a stage 1 conversion, It has dark blue(4x4 injectors I think?) and a 4x4 dizzy cap fitted with magnecor leads. Its boosting to 1.1 bar but sometimes will only go to 0.5 bar. When started from cold the idle is all over the place from about 400-1500 untill it starts to warm up and then settles about 1000rpm but when you are driving it keeps stalling at idle. Every now and again it gets the usual cossie misfire too.

 

There is NO usual cossie misfire.
Get your BASE idle speed set to around 850/900 rpm, by means of the screw at the underside front facing on the throttle housing, AFTER disconnecting the ISCV.
Next get your CO checked.
tabetha

 

If its running race plugs say champion c57c it will hunt on warm up sounds like hes got a dicky turbo control valve though bout 25 quid 2 replace