If it helps in the troubleshooting, your engine should idle just fine with the MAF disconnected. I've got a 2001 3.0i as well, and have done this many times. You'll get a warning message (I forget what), but it resets itself when the MAF is reconnected.

So if you can't idle well with the MAF disconnected, you've got other problems, and it may be easier to find and fix those problems before bringing the MAF back into the system.

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2001 X5 3.0i, 203k miles, AT, owned since 2014