If you have EGR valvle codes have it changed quick. IF you don't this will only lead to more costly repairs in the near future. Once your engine sets a code it will no longer meter the fuel properly and goe sinto a default mode. When you continue to drive the next things that happen will be possible bad 02 sensor(s), clogged catalytic converter (or worse it could breakup and end up in your muffler), and or burnt plugs.
If you are handy go to your local Autozone and have them check the code to verify. Replace the valve or what ever other component is setting the code and hope other damage hasn't already been done. The cost of the repair will be made up quickly just in gas milage.
Also, contrary to popular belief, always run premium gas, it really does make a difference.