645ci E63 bought – pair of questions

Hello guys, I got myself an E63 coupe a few days ago. Used, 130k kilometers. Full equipment. Now some questions : He consumes in the city with very slow driving mode approx. 23 liters at approx. 15 minutes city rides with previously cold engine. That’s not normal or ? Besides, he “saws” in the stand, i.e. the speed pin trembles, the engine turns up, down, down…When reading out came out false air supply and the engine control light is now also addressed. BMW dealer says I should change some parts, but they just want to sell. – Air mass meter – Differential pressure meter from the suction tube Since you think that these little things are going better afterwards and especially the high consumption goes down. Maybe I build myself a gas system, then the whole is not so bad Thanks for your answers !