Just a quick one, Do all WRX'S idol at about 1.5/1.75 k revs. Mine has just started doing this but didnt when I got it. Seems like if you rev it the rev's drop back down to about 0.5 k revs.
You might have anything from a vacuum leak to a dirty IACV, dirty MAF sensor, dodgy MAP sensor, Lambda sensor fault. Without plugging in and noting what happens when it does it's thing it's all just guesswork.
You're in France. I'm happy to come over to France and plug in, and probably remap your car while i'm at it but you'll have to take care of my travel expenses although it looks like accommodation is catered for.
