galant3.8

Hi, I have a 2009, 3.8L Galant (Not Ralliart), Gulf specs. I am currently facing tough gear shifts between 1st and 2nd shifts. Specially when driving in low speeds inside the city. What I mean by "Tough shifts" is when I accelerate a little bit and leave the peddle, I hear "Dopp" . And I feel the gear box become loose horizontally! The process: 1. Accelerate in low speed, 2. leave the peddle, 3. Press again, 4. Leave the peddle or brake. This problem exists also with my friend 2008 Galant. The disaster is that the agency doesn't have any idea about the cause of this! Any help is highly appreciated