850 estate 2.5 ltr b5252 engine

i wonder if any one can help with this please. the idle rpm has dropped down 600/650.when you push down the accelarator slowly it drops down to under 500 then picks up as you continue pressing down accelarator

ihave checked the manual and tried fault codes for the injection system (module A socket 2) and it showed no faults i also cannot find
any leaks in any pipes.
i would be grateful if any one has any ideas

 

Try cleaning the throttle body and idle motor good adn see if it helps.

If not then the throttle position sensor might be on its way out.