Car shakes/Vibrates around 23-35 m.p.h. when changing gears
 

I have a 2004 Acura TL Navigation, 104k miles. Automatic Transmission. On slow acceleration around 25-35 m.p.h. car shakes/vibrates right before changing gear, feels like it's skipping a beat... I just changed spark plugs, thought it would fix the problem, but it didn't... Anyone else experiencing problem? When I took it for oil change, I asked them to check my mounts, they said they were fine. Any help would be appreciated. Thanks...
P.S. I always use 93 gas...

Car shifts gear smoothly...

It's a well known issue with the automatic models. Try a search for "racing ATF" and "Interesting conversation with my trans builder". These threads will tell you everything you need to know.

You need Redline Racing ATF and the 3rd and 4th gear pressure switches to cure it if it's not too late already.