Possible 02 sensors issues

I know nothing about this stuff. But just wanted to report my experience couple years ago.

Was driving on the freeway, heard a kaboom and suddenly lost about half my power. Hobbled to exit. Took MH into a repair shop. They said O2 sensor popped right out of the exhaust pipe (somewhere along the front half of coach). Guess it was just hanging out. They replaced the sensor, sealed up the hole and I was on my way.

I also have the Workhorse 8.1L.

Rockauto didn't show plug wires. My mistake! Looked for 8.1 in Chev pick ups and are shown there.
Coil packs normally don't monitor output of coil packs. At least my coil pack vehicles don't!

Assume this is the 8.1L?

When you say "no code" did you actually connect a scan tool or are you just going by the fact the check engine light (CEL) isn't on? If the latter, scan it anyway because if there is definitely a code set stored if it runs like that.

Coil pack would throw a code and light CEL for a misfire. Any issue with the O2 sensor will throw a code and light the CEL. Confirm when you start up that the CEL itself is working.

Since the problem started when you changed the plugs and wires I would go back and re-check your work there. Plugs should be AC Delco 41-983. Check gap and also check that new wires are seated with di-electric grease on both ends.

When you changed the wires, did you move the steel sleeves on the plug ends to the new wires? Those heat shields are essential given proximity to the exhaust manifold.

enblethen wrote:
You should not have plug wires. Coil packs should connect to short "wire" to connect to plugs.

There ARE plug wires. The coil packs are on the valve covers, but the plugs sit below the exhaust manifolds, so there are actual plug wires.

You should be able to see issues when you leave the scanner on between the sensor. You could have irregularly or sound rough when it idles. A faulty oxygen sensor can impact your engine's timing, combustion intervals, and stalling. They don't last fore every. You should have lost some mileage.

Could be coil pack. Output would not throw a code.
Pull plugs and look for a carboned up one or two.
Take high voltage connection inside coil pack. Look for rust on screw connection.
You should not have plug wires. Coil packs should connect to short "wire" to connect to plugs.