i have a 04 audi a4 1.8t fwd auto and it has a few problems that im trying to fo fix..

first of all wen the engine is on and the car is idling it shakes and rpm goes up and down randomly, i changed all spark plugs and ignition coils and didnt solve the missfires. plus the car wastes twice as much gas as usual because of the missifre i suppose..

i got it checked in different places and they all tell me different stuff so i dont know wich one to believe since i dont want to start changing parts that dont need to be changed..

some told me it might be an air leak, some said fuel pump, some said mass air flow sensor, and the last one i went to that seamed like he knew what he was talking about said its the throttle body positon sensor.

Another problem i have is that when im driving, the car all of a sudden goes in limp mode and then the car goes in neutral by itself and i have to stop the car, hit the break, and then accelearate again in order to work so i dont know if these problems are related or not

I need some advice in what part is causing these problems if anybody can help

 

limp mode could be from seriouis engine problem code being generated or from TCU error. Have you had a full scan done properly?

 

^^^ exactly- get a full scan done then post all the codes up... We should be able to help better then.