Hello!

I’m having issues with my 2008 Mini Cooper S R56. Engine has 62K miles on it.
last year I had the head rebuilt due to the timing chain abruptly failing. Ever since getting it back, it’s been running like a champ except over the past month or so, issues have been popping up.

Hitting highway speeds, I’ll get a drop in power, and CEL starts flashing. Pull over, shut the car off and it fires up fine with no misfire signs. Going up steep hills (I live in Seattle), I also get a drop in power as well, but no misfires. Drives normally once over the hill. The temperature warning light gets triggered once in a while, but it isn’t frequent.
When I park the car and shut it off, the fan tends to run for a considerable amount of time.

I replaced the low pressure fuel pump tonight, and it started up fine, but still runs rough unless the RPMs are close to 2K. Shut the car off, attempted to restart, but now I just get a click from the engine. Fuel pump engages, dash lights turn on, etc. My guess is the battery is bad due to the fan running after the engine is off.

is there anything I should be looking for/at with the super rough idle? Any attempt at driving kills the engine, so it’s stuck where it’s at unless it’s towed. I’m getting no error codes at all. I did have a faulty O2, and MAF sensor that triggered codes, but those have been replaced - hence no other codes showing.
From reading posts on here, it sounds like it could be the HPFP, which with that price tag now seems like a nightmare to deal with, and I should be getting some error code it it were.

Any tips/suggestions/thoughts/solutions are very much appreciated.