Truck is surging under de-acceleration and threw a P0430 Code. Time to see what's going on now
It's a catalytic converter efficiency code. My wife's Buick threw this code last year. Had to get the cat repalced under GM's emmisions warranty. Tried swapping rear O2 sensors side to side and the code didn't move one side to the other and off to the dealer it went.
I didn't have any noticeable change in drivability though. Wonder if there's something else driving the condition that manifests in that code.