Malaysia is a one of the cheapest country to travel in the world. You can't finish Malaysia in 1 trip, basically split into 2. One is West Malaysia, another one is East Malaysia. West Malaysia, you can cover it minimum 5 days, with hopping each city. Kuala Lumpur, Melacca, Genting, Ipoh.
Island you can explore Langkawi/ Redang/ Perhentian and Pangkor. Malaysia food is delicious and most delicious food are not serve in air condition restaurant. Thats the truely Malaysian style. Average a meal are USD5 per head include drink. East Malaysia, you spend 1 trip in Sarawak, 1 trip in Sabah. If you want to combine it, then it will be longer (10 days) covering, Kuching, Miri, Tawau, Kota Kinabalu.