Black bars are usually the result of a mismatch between the aspect ratio (16:9 etc) of a film and the aspect ratio of the source material. If you export a 4:3 clip as 16:9 there would be black bars on either side -- if you export a 16:9 clip as a 4:3 movie where will be bars at the top and bottom (letter boxing). The only way around this is to use only a part of your original; crop it to fit the export ratio. I've little idea how you would get bars at the top and bottom AND at the sides!
Did you mean anamorphic? That's distorting the shapes of the images on film. They shapes are restored only by projection with a matching lens system. You can do distortions in MEP by zooming more in one direction then the other -- do NOT maintain aspect ratio.