I have the same problem with mine, disconnected ISCV, the fact that the idle is able to raise revs and drop shows it to be working, rather it is being told to do this. I often thought it could be my CTS causing problems but car otherwise runs perfectly fine so not to fussed about it.

I would check CTS and TPS, won't be air leak otherwise it would happen all the time. What chip do you have?

Martin