P0300, p0131, p0172
#3
Troubleshooting
I've monitored the misfire counter and also watched the O2 voltages. Seems like 1/1 isn't switching all the time. Actually only when throttle is applied. Also the exhaust smells of sulfur and at idle an tone will come on and the CEL will then blink, after a bit it repeats and goes solid. I can't seem to find a correct firing order for this engine. I doubt my scan tool would switch the banks but it seems like the symptoms of the 2-4-6 cyl misfire head replacement issue.
#5
O2 swap
After poking around some more I noticed there was oil on the 1/1 sensor. I've tracked it down to the PCV leaking at the rear of the passenger side valve cover. I've resealed that (major PITA) and will install a new O2 today. Also a PITA, they only wanted tiny hands Rob Lowe working back there.