Computer problem
2008 Acura TL 6 cyl Two Wheel Drive Automatic 8400 miles

There is a issue for my Acura 2008 TL with 8400 miles

Sometimes it runs smoothly (quick acceleration and stable)
Most of time it runs not smoothly. (slow acceleration and shimmy)

When I turn on the car if it runs smooth and it will be smooth all the time in this trip.

When I turn on the car if it runs not smooth and it will be not smooth all the time in this trip.

Dealers is not able to find out the problem and says it is normal.

Any suggesiton is welcome.

Thanks

Vincent Lo