My brother is on his way home for Thanksgiving, and he had an incident this morning where out of nowhere his car started running badly, lost power, and threw a CEL. When three other motorists ended up at the place he pulled off the highway, they realized that they had all bought gas from the same gas station up the road a little ways.

Details are a bit fuzzy at this point, but apparently he found a shop to get his tank drained, and I presume fuel filter changed, and he's back on the road.

Is there anything I should look over before he heads back?