Is A Nightmare on Elm Street Part 3 in 3D?

No, you are confusing the Nightmare on Elm Streetfranchise with the Friday the 13th franchise. Friday the 13th Part 3 (sometimes called Friday the 13th Part 3D), which came out in 1982, was shown in 3D in theatres, and a special 3D version was released on VHS or DVD, or both.

A Nightmare on Elm Street Part 3: Dream Warriors (1987) was definitely not a 3D movie. Ever.

See the Related Links below for more information about each movie.