Duke3D: Automatic vertical view angle creates "flickering" effect in some situations

This can be noticed specially on E1L6. When going up the slope to the force field control tower, which uses slopes combined with horizontal sprites laid out to cover gaps, near the edges of some of those sprites the view angle is adjusted suddenly a high amount up or down and then corrected, creating a flickering or heaving nodding effect. MR incoming with video to showcase the problem.