schil01-camper

I've had a miss happening at high RPM and when I unplug the O2 sensor it goes away. Plug it in and it misses at operating temp. The 'miss' here is an engine stumble once every few seconds, somewhat randomly. You can see and feel the engine shake a little when it does it. I'm doing this at no load by opening the throttle. When cold it's not there at high or low RPM, presumably because the O2 sensor isn't in the loop until it's warm. It's the denso part, only about 6000 miles old. I ordered a replacement but I'm wondering if I'm eating O2 sensors due to the header it's installed in.
The header is a Hedman HED-39490 header. O2 bung is partway down one tube. Here is the header and O2 sensor placement.

I installed a new head and the header about 4000 miles ago and I cleaned the EGR at the same time (though I can't be certain it's not EGR related).
I'm going to install the new one and watch out for a future failure but I'm wondering if anyone has experienced this kind of issue before. I'd like to avoid eating multiple O2 sensors if possible.
It was acting up a lot this last weekend so I pulled out the O2 sensor and "heat cleaned" it with a propane torch. I tested the voltage output at the same time and it seemed to respond ok but the O2 connector on/off = miss/no miss test is still telling me it's bad. There was only minor carbon build up and it' didn't look bad. maybe I just have a bad one and after this it will be fine... Perhaps it's not related to the header at all? so many questions and I'm feeling clueless about this so any thoughts would be appreciated.

schil01-camper

I've found what appears to be a work-around for this issue.
My symptoms were much like what was reported in this tread: https://www.yotatech.com/forums/f116...advice-213660/
The solution there was to cut down on EGR air volume with a baffle plate using a smaller hole (1/8" instead of like 3/8"). I know it sounds strange, but read that thread if you have similar issues.
I thought the O2 sensor was the culprit, and indeed it ran better with it disconnected, but it was not a sure-fix and I think the O2 sensor is fine. With the EGR totally blocked off on mine it seems to have solved the high RPM miss under no load issue. I'll monitor and find out if that remains a fix over time.