Check engine light is on Car running fine fill up with gas starts hard

 

If the purge valve is stuck open it could produce that problem.

A lot of times continuing to add fuel when the fuel nozzle shuts off can contribute to a problem like this. It sends charcoal granules into the vapor lines and causes problems with the emission controls. Over filling the fuel system sends liquid into the vapor only system and it is only a matter of time before the results begin to appear.