01 Ram 1500 3.9L O2 sensor

Hey, I've got an 01 Ram 1500 with the 3.9L, and the engine light came on. I changed the upstream O2 sensor, it ran fine, then the light went out. A couple days later, it started chugging & stalling, the light came back on, then it ran fine. Now, the light's still on & the stalling is back. Anyone know what the deal with that is? If it's just a matter of resetting the computer, can you do that by unhooking the battery for a minute? I heard that if you disconnect it (and then reconnect it) that it wouldn't start then. I haven't risked it yet. Anyone have any ideas on that?
Thanks

Update: Well, I unhooked the battery, then hooked it back up, and it started. The light was out, and it ran, then it started the chugging again & the light came back on. So, I'm back to where I started.

When you switched out the O2 sensor, what kind of condition was it in?

It was brand new, out of the box. I changed it at the dealership.

Problem solved: Well, all it was, was that I didn't quite get the electrical connection connected. I'm glad that that's all it was.