Rain and limp mode
 

2005 Mini Cooper S with ~122k miles.

My car will start in limp mode about half the time if it's raining (or even just wet outside). Sometime I get a CEL, this morning I didn't. Stumbling, hesitation, and generally runs like crap if I use much throttle.

This morning I turned the car off and then back on at a stoplight and all was normal and smooth again.

Is this just a belt slip on start up ? I just replaced the belt this summer. It's been happening for the last maybe 40k miles. Maybe my tensioner is on it's way out? I'm probably due for spark plugs soon but I don't think that's related.

Have you scanned it once in limp mode?

I have not. Didn't get a CEL this time. I should have done a scan other times but didn't.

Happened again. Starting to think it's an electrical issue...