Odd throttle response from tick over

Hi all, I've got this odd throttle response from tickover where you very slowly and gently push the pedal down but instead of increasing the revs smoothly it suddenly jumps to about 1600rpm

Initially i thought cable but this appears fine, the fault is still there when you increase the rpm by hand at the throttle body.
It was suggested (on Facebook) it might be the TPS, so resets were done, no change. TPS checked but appears to working fine with a nice smooth increase in voltage as the throttle is opened.
IACV, its not hunting, no idle issues starts and runs fine. The only thing i'm not sure of is that i can hear it ticking/stepping occasionally while the ignition is on but the engine is not running (I bought a cheap OBD reader so have been playing this afternoon so the engine has been on/off). Not sure if this is common behaviour for an IACV when the engines been run in short bursts?

I've cleaned the IACV and throttle body, nothing too bad, no splits in the pipes etc and all looks ok. Nothing untoward from the OBD reader either.

Any suggestions greatly appreciated before i start throwing (more) money at it!?

Is the throttle action sticky at all or is everything silky smooth but you still get a jerky response from the throttle? If there is something sticky, this may be your problem.

Annoyingly it's all smooth! When the throttle body was on the bench you can see the butterfly opening in time with the rotation of the cam the cable attaches to so I don't believe there's an issue with that.

There's a bit in this thread unstable idle about throttle position of 3.9% open which i can see on the OBD but this then jumps to about 4.7% obviously in time with the sudden rpm increase. I've tested the TPS but this would appear to be working correctly and smoothly and again in time with the throttle operation so I'm not sure what to check next?!

Then sorry, this is beyond my knowledge. In my defence, it is very common for the pedal to be overlooked when dealing with a sticky throttle. Hopefully, someone with more knowledge will be along to offer better advice