Not water in my tank. What is it?

I have a 04 dodge neon and I had an oil change about a month ago. Since then it has been acting like it has water in the gas tank and will kinda jump when I'm not pushing on the gas pedal. It has occassionally died at stop lights too. Also, the check engine and oil lights will randomly come on and go off. I was told that the lights are an electrical sensor but I kinda wonder if they have to do with what is happening with my car. I have taken it to mechanics and they can't figure it out because it doesn't do it all the time (it's random). Please help?