Hi nordzway, if you post the 3DM file I can give you some better tips.

re: path constrain - there is the Flow function under Transform > Deform > Flow, where you can map a shape from a straight line backbone to a curved one. To use that way you would just extrude your shape to make it initially straight, then use Transform > Deform > Twist to twist it, then draw a line down the center of it and use the line as the base curve for a curve to curve Flow. There is more information on Flow here: http://moi3d.com/3.0/docs/moi_command_reference8.htm#flow

It's also possible that the glitch you show above is just a display artifact and the actual surface is ok. That's something that I could check if you would post the 3DM model file instead of only screenshots.

If sweep is generating something bad between 2 profiles, it's probably because of the twist reduction mechanism in Sweep - normally sweep tries to align shapes in such a way to reduce twist. If you're running into that, then you could try initially placing the 2 end profiles for the Sweep to be non rotated, then do the sweep and introduce the twist by rotating the end profile after the sweep is done using history updating to update the sweep. That's another thing to try.

- Michael