Pulling my hair out here. When started idles @ 2000 rpm for a few seconds then hunts up and down 800-1500.
Ive checked all pipework for airleaks , changed the dumpvalve, intercooler off and all pipes etc checked.
When the idle control valve is unplugged its not nearly as bad but still evident. Track day tommorrow and I dont want her to blow..

 

I'm wondering if your ISCV is sticking and needs a bit of cleaning, wd40 spraying onto it?

Other than air leaks or fuel issues, it could be maf or lambda related. I'm assuming that this hasn't occured after fitting mods.