It not clear to me, do the codes come back each time you let it idle for a long period of time or just that once. Do you know if the the codes were present before you let it idle? The o2 sensors your replaced were those pre cat and did you replace them with OE or OEM sensors?

Since you have driven it 200 miles and codes have not returned and there are so many potential causes I would not do anything other than periodically check to see if they do return.

Upallnight's suggestions are great but if you don't have either software, your thought of a smoke test is a good idea. If your are not familiar with INPA I think it has all long learning curve. I have a Apple app similar to Torque that I find addresses most of what I have needed and is fairly easy to use and somewhat intuitive. Sunny5280 could also be on target but you don't have a rough idle which is usually a bad MAF indication. Easy to clean the MAF just in case.

At this point, I think replacing anything is a shot in the dark.

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