Reset the CO - hot and at idle it's fluctuating between 0.4 and 1.0. Probably about as accurate as I'm going to get with a £80 Gunsons gasmeter.

Without the ISCV plugged in it's quite stable now, but as soon as we plug it in, it goes nuts up to 2000rpm and drops down and back up all the time. Just did a second video showing it, this afternoon: