Rough and stalls on start but then fine
 

Hi!

I have an R56 Mini Cooper (not turbo). It has been fine, but the other day, I started it, and it was very rough and almost stalled. This has continued since, and sometimes it has stalled.

Once it is warm and running, it is fine, but until then, trying to drive just ends in the accelerator not responding and the car being rough and or stalling.

I watched a bunch of videos, lots of people saying replace this, that or the other, but they all seem to have different symptoms, and I am not in a position to diagnose by replacing hundreds if not thousands of dollars of parts that may be fine. For the same reason, I'm not keen on taking it to the garage as I worry that that is exactly what they will do.

The engine light does not come on, there are no fault codes, the temperature sensors seem to have sane and consistent looking values, the short-term trim drops to -24 briefly but then levels out at 0 +/- 1, I can't hear any hissing or leaking and the oil cap is secure - when removed, there is pressure pushing air out, not sucking it in. I haven't noticed any misfires, and car scanner doesn't seem to show any.

I'm not a mechanic, but I can make sense of most of the videos and can give most things a go.

I'm keen to hear any ideas on what could be going on and also wondering if it is safe to drive when it is warm?