2003 Kia Rio Was sputtering at Idle

Engine Performance problem
2003 Kia Rio 4 cyl Automatic 101815 miles

Yesterday my engine check light came on. I was near home, so I just decided to park it in the driveway. Later that evening, I had to go return a movie, and as I turn on my engine it starts to sputter. It hasn't been sputtering for a few days now (I assumed because it's warmer), but it sputtered every time I turned it on during the cold winter. Anyways, it sputters a little and goes normal, I back out, and as I slow down to accelerate, it starts sputtering very deeply, as if it's going to die, and doesn't react very well to me pressing down on the accelerator.

So, I drive my car back onto the driveway, and use my other car to deliver the movie.

Today, I start it up, and it sputters. Not horribly, but not good either, while idling. I shut it off and figure it's best to leave it alone until I can get it to a mechanic. Then I decide to atleast take it for a spin around the block and see how the engine acts at different speeds.

I start it up, it sputters (but not as badly as before), and then I go for a drive. It all seems normal, and after a minute or two of driving, I pull into a church parking lot and slow down to a stop. No sputtering, completely normal. I switch back and forth some from D to N to P and then I drive to my house and shut off the engine. For good measure, I start it up again and let it idle for 20 or so seconds. No problems. No sputtering.

However, the engine check light continues to remain on. It doesn't blink, and it's orange (I don't think Kia's have the variety of signals, but JIC).

Any suggestions?