[Dannehhboi]

Hi everyone, hope you're good!

I've got an issue with my E92 320i that I recently purchased that I am trying fix and I was hoping for some advice as to what to try next and in what order.

So when I cold start the vehicle, it is completely fine and starts immediately. There is also no issues with the driving / idling of the vehicle. However, after driving it for some time and switching the engine off if I go to start it again before letting it cool it will struggle a lot to start. It will start cranking, but could take up to around 10 seconds to actually fire up and sometimes it doesn't even start at all and I have to try again. It also sounds like its spluttering and shaking like a very bad misfire.

I had codes for the MAF which I changed, and then a code for the MAP which I have now changed. The codes and EML have gone but the issue persists. The only other engine related codes I now get is an intermittent code for the brake vacuum and an intermittent code for the NOX / Lambda sensor.

I have a list of potential culprits, but I am unsure what to start first so if someone could help with that, or let me know if I'm missing anything that would be great.

HPFP, fuel injectors, fuel pump relay, crankshaft position sensor, starter motor, potentially battery?

Thank you!

I will also mention that a previous owner remapped it, so is this the cause?