Troubleshooting is always good to help narrow a problem and avoid spending unnecessary money on parts. But this N52 is not rocket surgery. It's been around for over a decade. And they are very well known for neding certain things every 60-100k Miles. VCG, Plugs, Coils, and all vaccum hoses and rubber in the intake system replaced. Every one I've ever worked on has been the same, if I try to replace individual parts based on troubleshooting, I end up chasing my tail and having problem after problem. So I replace this stuff in batches now.

Another issue that causes rough starts(will also cause hesitation from a dead stop)is the DISA valve. Easy enough to pull it out of the manifold and check it. If it's not closed when you pull it out, it's no good. Another potential problem you might have on top of what seems like a bad vaccum leak and potential O2 sensor.