Lately I have been shooting in Manual mode and Auto ISO for birds and wildlife. I set the SS to 1000-2000 and shoot at f8 on my Nikon 300mm f4 because I have read this is where the lens is sharpest...by doing this the ISO is higher that at f4.My question is will I get just as good of sharpness if I use Manual Mode f4 with an Auto ISO? The Camera is a D7000

The mode you use doesn't matter, the only thing that matters is shutter speed, aperture, ISO. Whether you set each of these yourself or let the camera choose them.f/8 is usually a safe bet when it comes to the sharpest aperture of a lens, but some lenses are already very good wide open or at a wider aperture such as f/4 or f/5.6. The only way to know for sure is to do a bunch of test shots with different apertures (obviously of something well lit and non-moving).Even if your lens is sharpest at f/8 it may pay to use a wider aperture because the advantage of a lower ISO value can easily outweigh a slight hit in sharpness from the lower f number. (Or maybe not. Depends on the lens.)Also, do you really need 1/1000 or 1/2000? For birds some wing movement may not be a bad thing and that way you don't have to push the ISO so much.