I have a 2004 Buick LeSabre with 64,000 miles and it's in great shape but the only diagnostic code coming up, is an 02 sensor and yet, the car tends to jerk forward while in drive sometimes.

I'm pretty sure there's no "cleaning" of an O2 sensor. When the check engine code says it's bad, replace it. If you didn't actually get a new one, I would try that first and see if the problem persists.

I have a slightly older model and it wouldn't idle perfectly when warm and in drive (at a stop). It wasnt a trans issue in my case it was a issue with the ignition control module that caused the rpms to increase and decrease at idle. I thought it was atrams issue at first. Is yours similar? There are so many factors that need to be taken into consideration, to start is the problem like mine was (stopped in drive) or is yours at different speeds? I did my O2 sensor and that helped my gas milage mainly and it also smoothed acceleration. As reelin68 mentioned, there isn't a procedure for cleaning the O2 sensor that ive ever heard of but and the major O2 sensor manufacturers usually recommend replacing them (regardless of any malfunctions) around 60,000mi if i remember correctly. My suggestion is to start with replacement of the O2 sensors (my model year only has one sensor, yours probably has more) ALL of them, and do so with ACDelco or NTK brand, both are OEM types.