Hello, I did not find a suitable answer in the forum!! I installed a sports air filter on my e28 520i and then it started to stutter when giving gas and sometimes took no gas at all! Have converted air filters again to original – no change!!…Steurung relays exchanged, All hoses, air mass meters works, everything cleaned, no success! Control times have been adjusted as well as valves! Please help, thank you! Lg