The diesel engines used in Vanagons have no throttle housing or AFM.
The air supply to the intake is neither controlled or measured. Diesels
do not need these because they do not operate on the basis of
maintaining a fuel/air mixture ratio. They have a mechanical injection
system which varies the amount of fuel based on rpm and pedal position
only. The air supply is constant at a given rpm. VW TDI motors do have
AFMs but they are not interchangeable.

Mark

Douglas Miller wrote:
>
>     Could the idle speed adjusting screw/throttle valve housing be my
> problem?  Is a 1.9 throttle housing interchangeable with a diesel or a 2.1L ?
>  Is the AFM on a 1.9L interchangeable with a diesel or a 2.1L?
>     Thanks once again,
>     Doug