Is Malaysia a federation?

Currently, no. From 31 January 1948 until 16 September 1963, the Federation of Malaya is the name given to 11 states. The states were Perlis, Kedah, Perak, Selangor, Negeri Sembilan, Johor, Pahang, Terengganu, Kelantan, Penang, and Melacca. It was eventually superseded by Malaysia.