I would suggest that the inlet tract (including Idle Air Control Valve ) is
in need of a thorough clean up. VOC recommend task is done every two years
to keep system on the ball.
Do you mean that you replaced all the inlet tract from filter to manifold?
The idea is just to clean it thoroughly. This includes the MAF, throttle
body, throttle stop microswitch and Idle Air Control Valve along with all
the hosing and electrical connectors. It is a good idea to ensure that the
PCV system is also clean and clear.