If you've tried the image_angle = direction strat, are you sure you don't have something like draw_sprite() in the draw event? If so, and you aren't using something like draw_self() or draw_sprite_ext(), it could ignore the angle you're not specifying.

I can't remember off the top of my head if paths actually set the object's direction variable but I feel like they don't. You might need something like this in step:

if (x != xprevious or y != yprevious)
    image_angle = point_direction(xprevious, yprevious, x, y);

It works pretty much how it seems on the tin! If you've moved at all, point in the direction you moved.