Lumpy idle and throttle position?

[Kevbu]

I have a 2.0tdi cbab engine.
It seems a little rough on idle, sort of shudders the car, but only when it's warmed up.
Any ideas? Searching seems to give lots of info but nothing conclusive.
Using torquepro and Bluetooth obd thingy there is no stored codes but the only anomaly is the throttle position is at 90% and doesn't change when I move pedal.
Is that normal or do I need to change pedal?