Idling that high will be a decent vacuum leak. EGR leaking past will kill the engine at idle, not raise the idle speed due to oxygen dilution in the intake charge.

Not being familiar with the M104, does it have some sort of idle control valve? I know the V8's do and they can stick, or the module that controls them develops broken solder joints and causes exactly the behavior you describe. It mimics the throttle plate being held slightly open.

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Current stable:
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