2005 Kia Spectra Sputters and slows

Hi, I really hope you can help! The first time this happened was a few weeks ago, after I got an oil change from Walmart. My car will be going just fine, then it will start to kinda jerk back and forth, I can hit the gas, it revs, but slows and will not go any farther. I pull over to the side of the road, turn the car off, then on, and its fine for a while. Sometimes it will start to do it, then will "push" through it and be fine. I have had to pull over and restart twice in the last 2 weeks, but I can tell it's not running right. Please let me know if you need any more information, I am not good with car issues :) Ive read a lot of your posts on here and nothing seems to be exactly what is happening to me. Please help!