Car runs rough after fillup - 2005 Elantra
 

I just picked up this car - runs GREAT - except after filling it. Then she will sputter occasionally while driving. It will also stall sometimes at idle. Below 3/4 (approximately) she will run fine. Got any clues?

Purge valve possibly. Get the computer scanned for codes.

Check your evaporation charcoal canister for raw fuel. If contaminated you need to replace the canister and 2 check valves that are inside the 2 small lines going to the tank. The 2 small lines are next to the big fill hose at tank on the left hand side. The valves are small and are inside the lines. If you remove lines from tank you will see and feel the valves inside the line ends.