1999 2.5L v6 (es model)

My computer is throwing p0300 codes, jumping around to all cylinders, but only after it's been on for a while and the wheel is turned hard to the left. Take today for example:

Driving home from work in stop and go traffic, no codes whatsoever, car running fine; make a U turn after about 40 minutes of this driving and all the sudden I've got misfire codes for nearly every cylinder.

Any idea what could cause this? I'm thinking fuel components but I'm just not sure...