Thanks for the feedback. It's does not seem to have anything to do with any specific fuel. It happens randomly, regardless of fuel stops. That's also the problem, it's so random that it's hard to change something (like the octane) and know if it makes a difference. On my last trip, it happened on a hill an hour and a half into my drive out and fifteen minutes into my drive home. Both times it happened once and never repeated for the rest of the drive, even under similar conditions. There are no stored codes.