overheating problem

[wkg96rs]

my rs is overheating only when the car is at idle after reaching normal operating temperature. if i tach it up to 3000 rpm and hold it there for 15 seconds, it goes down again... i figured it might be the thermostat, but i changed it and it didnt help. just replaced my upper hose, as it looked like it grew a tumor. really hoping my radiator isnt blocked...

 

[JPGRL]

I searched for "overheating idle" and found "overheats while sitting" on the first page of results:
http://www.dsmtuners.com/forums/showthread.php?t=152916&highlight=overheating+idle

There's a few good things to try in that post.

(And, just wondering, why'd you post this in the drivetrain section?)