ZX2 wont accelerate

I have a 2000 zx2, I dont know much about cars, but I am hoping to find somethign here. I am having trouble with my car accelerating. It wont go to far above 60 on the highway, unless i punch it. I just had a oil change, and I used a fuel injector when I filled up last. I have no Idea what to do. Any suggestions are welcome at this point. Thanks!!!

need more info... does it lurch? have you had a tune up lately? how many miles are on it? as much info as you can give us the more we can help... oh and one more question. do you have pics?