You can try cleaning the MAF with MAF cleaner to see if that is the cause. I go through MAFs quite often, have never had one fail to the point the engine wouldn't run. Early symptoms are usually the vehicle wont' accelerate normally and engine roars.

Would like to hear more about where the smoke was coming from. If at the base of the runners that could mean you have an intake manifold gasket gone. That would cause a huge vacuum leak. I would do a vacuum test. Since it is not running it would have to be a smoke test which is the best test anyway. There are several youtube videos detailing how to build one, very easy.

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X5 4.6 2002 Black Sap, Black interior. 2013 X5M Melbourne Red, Bamboo interior
Dallas