f:

Between the airflow sensor and the fuel distributor is a tower (that may or may not still have a plug installed) with a 3mm hex socket adjustment screw inside. That screw is spring loaded upwards, and can be pushed down with a hex key installed. When pushed down it engages a second screw in the arm between the airflow plate and the plunger of the fuel distributor. Try a CCW (lean) move of about 1/8 turn (with the engine off), and then proceed in steps of no more than 1/8 turn. Remove the adjusting tool each time before restarting the engine.