O2 Sensor Codes Keep Returning

[alleycat]

I scanned numerous old posts threads before staring new post but I found a great deal of inconsistency in the posts surrounding these codes. My 2000 w/ 240K miles has been running very well. Recently I noticed rough idle (which I may have incorrectly described as misfire) for a couple minutes at start up and then normal. Also occasional rough running at highway speed for a couple minutes - then back to running normal. No CEL light was on.

Then today after 50 mile trip CEL light comes on. I had scan done which cited codes PO130 (Bank 1 Sensor 1 Circuit Malfunction) & PO133 (Bank 1 Sensor 1 Slow Response). Is this a common set of codes which is just pointing to O2 Sensor? Or could it be any number of possibilities. All help appreciated.

Well its scary when you do a search and your own post comes up from eight months ago. 3000 miles ago in April when I posted this, I followed through and replaced drivers side front O2 Sensor with a Denso. Cruiser ran like new again. Then about 500 miles ago, intermittent rough running started again, mainly at highway speeds with warm engine. Yesterday it finally threw a code - same as last time P0130 & P0133. Question is: is it possible that the new O2 Sensor I installed back in April has already failed or am I chasing a bigger issue and the codes are only the symptoms. By the way I have replaced all coils, spark plug seals, plugs, and cleaned MAF within the last year. I have read many threads concerning rough idle and the diagnosis are all over the map. Any help appreciated as I like to avoid a trip to the shop. Happy Holidays.