Knocking noise or exhaust leak

So I have a 2008 Silverado 6.0 v8 around 160k
miles. I recently changed the oil in it using 5w-30
synthetic high mileage oil. I also discovered a small
hole in the exhaust pipe. So I changed the oil in the
truck...2 days later I patch the hole in the exhaust
everything is fine until I drive about 40 miles.
Whenever I get to about 40 miles I hear a small
ticking/knocking noise and it's annoying. And when
I come to a stop my truck sounds bad, like a diesel
almost just idling. But after the truck cools and sits
for a while and I start it up and drive short distant
everything is fine. No knocking, truck sounds good.
Only after I've been driving awhile will the noise
appear and sometimes will even go away like the
truck fixed itself. Also my engine light came on the
same day that I patched the hole in the exhaust.
Took it to autozone and th readings came back that
my oil pressure sensor needed repair and to
reprogram ecu sensors. Confused and need help
trying to pinpoint what's going on