My bike surges/hunts on a steady throttle.  I've had the manifolds re-installed to cure a leak, then new manifolds, then new plugs, and most recently new coils.  Problem is always fixed, but only for 50-100 kms, when it comes back. Problem has been there since new. Bought March, 2022, so warranty about to run out.
Anybody else had this issue ?

Have you balanced the throttle bodies?

It a fueling issue and shows up in all these bikes some a lot worse than others. A a proper Dynotune at a specialist will fix it but it's not cheap. Hope that helps. What happens is they re calibrate the throttle when ever it goes in for these problems. How ever after that 50 - 100 kms it returns to what the ECU is demanding. Mine is tolerable but not ideal.

Is there a fuel pressure regulator on these bikes?  Can the fuel pressure be monitored while riding?