not unusual...
Is the AC or defroster on when this occurs? There have been a few TSBs regarding the surging you describe.
You might pick up some CRC Electronics or their specific Mass Air Flow cleaner (from any auto parts store) and try cleaning your MAF. It's just aft the engine air filter (you'll need a T-20 security torx bit to remove the 2 screws holding it in place).
a diy write up how to hosted on Mike Focke's page (scroll 1/2 way down) (cut and paste below link)
sites.google.com/site/mikefocke2/checkenginelightcausedbymassairflowsensor
and you may want to clean your throttle body at the same time. diy directions Pedro at Pedro's Garage (cut and paste below link)
pedrosgarage.com/Site_3/Clean_the_Throttle_Body.html
Other possibilities too but I'd start there
