Hi. vw polo gti year 2016 with 101789 km. , engine code DAJB , engine does not run smoothly limps loses strokes , made diagnosis presents this cod. Error P21F9 FUEL CONTROL SYSTEM "B "MIXTURE TOO RICH AT MINIMUM, BANKED 1, wading through the parameters in motion there are many missed ignitions, tried to replace the spark plugs but the problem persists strange thing that in diagnosis the error code is active but goes away and no error appears and then reappears intermittently, last thing accelerating hard and releasing the pedal there is a strong vibration from the doors of the distribution, could you give me some indication. I thank you in advance. Thank you. Regards