high idle speed M110 280

[G-Man]

I have the M110 2.8L dohc six in my '84 G-wagen. The engine runs way to fast at cold idle, sometimes nearly 2000 rpm.

I know that there are a couple of parts that could be responsible. The warm up compensator, which is painfully expensive, and the aux air valve. I have checked to make sure that the throttle plate is closed all the way. I have adjusted the idle speed screw in all the way.

If the engine is run up to operating temp, the idle stays up. If it is warmed up then shut off for a few minutes, the idle will come down.

Am I correct in that the WUC controls the opening and closing of the aux air valve? Does it control anything else? I was told it uses a bi-mettallic strip as a temp gauge, is this true?

So do I have a faulty WUC that is sending bad signals to the aux air valve, or a slow reacting air valve that doesn't respond to the WUC?

Help! I can't stand the high idle and it certainly isn't good for the transmission