check the spark plug cables?  Sounds like one or more are cracked.  At
night, lift the hood and see if you see any arcing near any of the
cables.

On 10/20/2005 9:48 PM US(ET), nissanstanza92 via CarKB.com took fingers
to keyboard, and typed the following:

Did the 'tune up' include new plugs?
While the engine is idling, pull off and then put back on, each spark
plug cable, one at a time. If the engine runs rougher than before with
the cable off, that cylinder's spark plug/cable is good. If there is no
difference in the engine when you pull off a cable, that spark
plug/cable is bad. Use a proper spark plug cable puller, or wear gloves
and keep all parts of your body off the metal parts of the car to
prevent electrial shock. If you have a rubber fender protector (used by
mechanics when working on car engines to prevent scratching the paint),
use that too.
More than likely, it is the cables rather than spark plugs, since spark
plugs are usually replaced with a tune ups. Your car is 13 years old.
Have the cables ever been replaced?