When my Suburban hit about 120,000 miles, it threw an 02 sensor code. I changed all four of them and noticed an immediate improvement in the way the truck ran, slight mileage increase and more throttle response.
Separate note, recently, I had to replace mt drive by wire throttle body because it kept putting on the CEL with a TPS code. Again, the truck runs a little nicer.
I've always wondered if sensors got lazy with age, like they're not throwing a code but they're not as sharp as when they are new. It certainly seems that way to me.