'06 Pacifica Issue

I have an '06 Pacifica with 150,000 miles. Last week the engine light came on and we noticed while driving at slow speeds, it's like it will surge a little. It's like it accelerates/slows/accelerates/slows/accelerates. As far as I know it has not thrown any codes. Has anyone had a similar issue or could maybe have a suggestion?

You could check the throttle for carbon build up. I have a 05 with the 3.5l engine and mine is always getting gummed up. It might be keeping the throttle from closing all the way so it is open even when your foot is not on the pedal. Also inside the plenum there are throttle plates (if that's what they are called) that get all carboned up too.