Rough idle, shuts off?

Okay, I'm going to tell you exactly how this car acts. When I first get in to go anywhere it runs great. If I go straight and get on expressway, I will drive it anywhere. But when I am going under about 30 MPH, starting and stopping, sitting in idle it begins to miss, vibrate, almost like a knocking sound. I have had it hooked up to a computer and all it shows is an oil sensor code and o2 sensor. They said it was old codes. Anyway, over the past few years I have figured out that I can take my battery cables off and reset the computer and it will run okay for about a day. And if it shut off in the middle of the road, I can jump out and unplug my cam sensor lol this car is crazy. No one around here knows because nothing shows up on the test, please help me figure this out. I'm a single mom with a job. I travel 30 miles a day to work, and this is the only thing we have to get us places. Thanks in Advance!