Over the past seven months or so, I’ve had an intermittent issue with my E39 where it randomly stalls at slow speed. Thankfully the issue only happened a few times spread out over several months. The difficult part about this issue was that the service engine light never came on and provided codes as a starting point for diagnosis of the issue. I suspected that either the camshaft position sensors were starting to fail, or that the MAF was starting to fail. Both were very plausible considering the symptoms and original mileage on those parts, which is 135,000 miles.