Tranny fluid is next, something I should have done ages ago but one time an indy shop told me I had a lifetime fluid and recommended against changing it. Now my transmission is getting notchy and I recently realized that I should have changed it a while ago, so I will be doing that this weekend.
I will see what happens after I change the tranny and diff fluids this weekend and if that doesn't solve it I'll get the 02 sensor. Actually, changing my front control arms helped a little bit so I attributed it to loose suspension components, but it happened again this weekend so now I know that wasn't the total fix.
I'll post a DIY on the sensor once I change it.
I hear the Bilstein HDs are awesome, and solid price point. Just a little stiffer...