The problem happens when engine is warm. When i stop at traffic lights rpm accelerates from 1 to 1.2rpm. No faults on the computer. Transmission is automatic, It is accelerating in P or D transmission mode.
I seen some posts in google that throttle body makes this happen or is there anything else to look at? Some said that transmission could be faulty( please no)
Please any advice to DIY.
Car is Jaguar XF 2012 sport

 

Could easily be an air leak so check fuel trims as per the many threads.