Hello to everybody!

I have a problem with my `02 Audi A4 B6 1.6 ALZ.
It is a problem that the car has since i bought it, and it has eaten all of my hard worked money until now.
I had a high idle ~1000 rpm wich was solved by replacing Throttle Body with a second-hand one(from germany).
From day one it had slow rpm returning to idle.
If i rev it in neutral(it-s a manual) the rpms drop fast to 1500 rpm and from 1500 rpm it goes down in steps until it reaches 800 rpm where it makes a final correction to idle. After all it stays at 800 with no problem. I have no codes stored. I could not find any air-leaks either. I have two MAF`s. A Hitachi one(original from the car) and a chinese one(not branded). With the Hitachi it has the symptoms from above, and with the chinese one it`s similar but the rpm doesn`t stop to 800 but 600 and jumps back 1200 and finally settle to 800. Any advice? Thank you !

 

the idle drops faster from any rpm higher than 1500 because of the FICO(fuel injector cut off) when the gas pedel is released completely. idle fuel trim resumes around 1500 rpm and slows down until normal rpm range. if it went fast the engine would stall on itself