intermittently stalling at lights

Every once in awhile my 98' grand am will stall at stop lights. I will push the gas and the rpms won't go up and the car will move very slowly. It usually only lasts a couple of seconds and then the rpms will go up and car will start moving again. Any suggestions on what might be causing this?

Welcome to AF.

It would be helpful list your engine...2.4L or 3.1L so others can weigh-in to help.