Gas Recirculation Valve (egr Valve) problems of the 2006 Mazda Tribute

After coming to a stop at an uphill grade--approx a 20 degree incline, as soon as the brake is released, the vehicle rolls backwards. The only means to prevent the vehicle from rolling back is to press on the brake again or to immediately press hard on the gas pedal. However, although the vehicle eventually starts moving uphill, there is a significant amount of backward travel prior to the engine producing enough power to overcome the backward roll. This is a safety concern since there might be vehicles directly behind me when this occurs. Fortunately, I have not had to stop at any steep grades that might cause the vehicle to rollback faster and further and possibly causing an accident.