4th gear trouble

[weatherdan822]

hello everyone. I just bought my new 2004 Mazda 3 hatchback. however, on my way home from the dealership, i noticed a small issue. When in 4th gear (atx), as i would let off, the car would begin to shake pretty severely before stopping as the car gained more speed. any clue as to what this is/how to eliminate this problem?

 

[cali_axela]

Sounds like a bad passenger side motor mount. Inspect it for wear (there's a good chance you'll see black fluid leaking from it) and if it's bad, have it replaced.