2000 Ford Contour jerking

I recently bought a ford contour 2000 from my neighbor, the car had been sitting for about 2 years. It would not start, I discovered it was the fuel filter, I also bought new tires. Now when you start the car the engine sounds great, but while the car is sitting still it idles normally, but then it idles low, like its about to cut off, this is while the car is sitting still, while driving it, it also sound like its going to bog out and shut down, but it doesn't. I have a check engine light on, but I have not did anything with it as of yet. I did have the oil changed and a new serpentine belt put on the idler pulley. Please help me diagnosis this problem. I bought this car for my 19 year old daughter who is just learning to drive, she has yet to drive this car.