Thanks for all the replies and physics theories, interesting reading
All sorted now by rebalancing carbs and resetting idle screws
Ticking over lovely again 👍👍👍
I'm curious as to what you did in what order. I understand adjusting the idle air screw but what did the rebalancing consist of - was it adjusting an individual slider height?
Rebalanced carbs using a proper vacuum gauge set and adjusting each slide height. All as per the Honda maintenance manual.