I've had an intermittent issue with the above codes. I installed a new Walker Premium O2 sensor and everything worked fine for a few weeks, Now the codes are back. Truck runs fine except for the codes. Not finding any real insights from other posts so I thought that I'd ask in a new post.
Thank you.

 

Start by posting up the exact explanation out of the Rave manual, we don't actually memorize the code meaning

 

The 1173 is a lean condition and the 0153 is a slow responding upstream O2 sensor. My hunch is that its a ground/voltage issue but curious what others have seen.

 

Start by swapping left and right and see if it follows the sensor, although it sounds like you have a vacuum leak on that side. What else was repaired recently?

 

No other recent repairs. I've had 3 upstream O2 sensors so I doubt that the sensor is the issue.
Thanks for the suggestion about the vacuum leak. I'll focus there.