I bought a used 2008 mdx. i feel the shift
Sorry, i cant really provide a solution without more details..
But i would say check the transmission fluid (assuming its an auto, since you said when it shifts)
If your transmission fluid is low, add some, then "Cycle" the fluid.
Start in your cars lowest gear (L or 1?) and keep it there for like 15 seconds. Then move up to gear 2, then (3?) or "D", then "N", then "R" then "P" with 15 seconds in between. The whole time your doing this, your holding the brake, and not moving. Your going from the lowest gear you can pick, to park. if your car has the manual mode and doest have "1 / L" or "2", put it in manual mode, keep it in first gear, tap to shift to second, and if it lets you go any higher, go to third, fourth, etc. with 15 seconds in between..
Do this anyways and see if it helps haha.. Good Luck!