Hello.

I have solved my problem :)

I've replaced the lambda sensor (LAF).

This is not a new sensor (2006 but only 10 000km).

I have bought it in France and it cost me 35EUR (+-55$), shipping includ.

Sometimes, at low load, I have a little lag when the motor coming out of "Lean Burn" mode.
But I think it's normal.

:)