to set car up get the co2 checked to see this is correct for ur set up..if car is modded then co2 will be higher.as a guide my stage 3 is running about 2.7% at idle.get car warm and disconnect iscv.set base idle by adjusting via the the bypass valve under the plenum at the front to about 850rpm then reconnect iscv idle shdnt alter /might lightly rise and drop again.i have a new one and it still sticks about 1000rpm sometimes.symptoms of dodgy valve are a bit hit and miss as with most things a fluctuating idle can also be caused by other things...are u having any specific probs..once all adjusted double check co again