Between 30-40 mph it feels as if the front end shudders and then ok at higer mph on 2008 Ford Explorer

Had transmission fluid changed but does it more now.

Asked by for the 2008 Ford Explorer
another thing to check is you may have an internal bulge in one of your tires.... which causes it to shudder at low speeds but once you gain speed it works its way out and the ride becomes smoother.