I have a 94 12v auto 4x4 3500 dumptruck with transmission issue. The truck has a problem when cruising at highway speed. The torque converter is continually locking and unlocking, tach fluctuates approx. 200rpm. If I accelerate TC stays locked and truck pulls strong, decelerating is not an issue. Only occurs when trying to maintain speed. I've found issue addressed on newer trucks but not on 94. Is there an easy fix that someone can send my way or do I have a more serious trans problem? Thanks.