1992 audi 100-2.3e idle problems.
 

Ok here is the thing. When i start the car the idle jumps up and down from 900 to 400. Then after 5 min of driving its OK. Its not only in the stage of warming up. When the engine is hot and i turn it off and on again it does the same thing. I checked the isv ( from another car) no diffrence. I checked for vacum leaks, found some, fixed them. Mechanics say that this was a common problems with thist car. They dont know how to fix it. I am starting to get frustrated. Do you think that could be the fault of the maf sensor or a bad fuel pump ( fuel pump sounds fine) if the fuel pump was bad the car would run bad not just on idle right? I checked the connectors to and they all look fine.

Anyone knows anything about this?

Please help.