Nissan Repair: 2001 Nissan Xterra, intake manifold gasket, air control valve

Question
Von.
My 2001 Nissan Xterra has a check engine light on and I retrieved two different codes P0505 and P0325.  Recently I had the intake manifold gasket replaced due to anit-freeze leak.  When I start the truck cold it almost stalls out for a second drooping down to about 400 rpm.  After that it idles at normal speed and it  runs normal and there is no problems when driving the truck.  When I start it in normal operating temperature it starts normal like nothing ever happened.  It also idles normal and does not have any power loss.  The two codes are for a Idle control valve and knock sensor.  Any ideas?  Please help.  Thanks

Answer
Arek,

Yes, replace both the knock sensor and the idle air control valve.  The knock sensor is a known part that has problems.  This will hurt mileage even though the truck runs correctly.  Second, the idle problem is associated with the idle air control valve as this adjusts the idle all the time the vehicle is running at rest.  When cold the idle air control valve bumps up the RPMS and that is what is causing the stalling or almost stalling problem.