First of all thank you so much Nathan for making this site!!

Ok, so once every month or so (mainly since it's been freezing here in Chicago) my X5 will begin to misfire once its warmed up, but only if I'm letting it sit outside to warm up or if I'm at a long light/train. It will show codes for misfires for at least 4 cylinders but sometimes all 6, lean codes and o2 sensor codes. The second I shut the car off and restart it, the car runs perfectly and the SES light shuts itself off after a day or 2. I bought this with a warped head for $900... I had it resurfaced and put all new vacuum hoses and obviously gaskets. I did not change the CCV (I know, I know lol), but the car isn't losing an excessive amount of oil. The car just hit 140K. Any help would be highly appreciated!