I have an 03 GT automatic while driving and when its in over drive it surges @ 35-40 and @45-50. When i take it out of over drive it still does it just not as bad. The things i have done are new ford coils, factory plugs, factory fuel filter, lucas injector clean, and EGR vaccum silenoid. Before i did the EGR vaccum silenoid i plug the vaccum hose that goes from the EGR vaccum silenoid to the ERG valve on the drive side intake. It seemed to clear it up alot. So, thats why put a new ERG vaccum silenoid on it but, it still did the same thing so i plugged the vaccum hose up again still does a little bit. Can anyone help me.