Whilst crawling through London yesterday, the car randomly decided it doesn't like to idle, erratic at best. Most of the time it would just cut out.

Pulled over and had a look at things, disconnected the ISCV for test purposes and the engine wouldn't tick over at all, reconnect and then it was back to dogdy idling. If you held it with a touch of throttle it was fine. Checked a few connections etc, but no joy.

That was last night. Parked up all night and just forgot about it and it then drove all the way home to Bristol the next morning without a hitch lol.
I took off the control valve and cleaned it up and refitted it, still idling fine. I cleaned it up a few months back already, as the car had/has a tendancy to kangaroo occasionally.

Any suggestions? My finger is pointing towards the ISCV, but any tips will be helpful.

Car is a 2.9 V6 btw.