1999 Plymouth Voyager skipping

I had van checked out at auto zone the check engine light has been on forever but the reason I had it checked was because of the skip that started as told I bought oxygen senser and put it on the van seemed to have more power but it still had skip, thinking maybe I got some bad gas I have put gas treatment with no change. The van when driving feels like its holding back its power but it will gradually pick up speed but once you stop it has a rough skipping vibration I don't have the money to put it in the shop so I am hoping you can give me some advice asto what and how to check next.I have a 7 and 10 year old I have to take to school every morning your help would be greatly appreciated. Again thanks for your time!