Rough Idle on Cold Start

[Guts1200]

What causes this? Once the car warms up, it idles fine. Had my plug/wires/coils and my motor mounts (along with a bunch of other stuff) changed recently.

Also, how smooth should idle be for a v12? Is it normal to feel faint vibrations in the steering wheel and seat? Not bad at all but can still feel it.

[jclausen]

You need to smoke the intake system when the engine is cold, you probably have vacuum leak some where or you coild try spraying the carb or brake clean at varous sealingg areas on the intake manifold when the engine is running, if the engine rpms go up after spraying you have found it. the 850 does have those rubber blocks/gaskets between the intake runners and the head that are common failure areas