When I did the heads/cam swap I re-used the old Bosch Platinum plugs because to be quite honest I FORGOT to buy new ones ...this morning I changed them out for new Autolite Platinums....

The passenger side looked perfect....light brown with no problems, the drivers side is a whole other story.....the plugs were pretty black and looked mildly fouled, three of the four had the electrodes opened up to .090-.100 and were bent sideways a little !!!!

I know I had/have bank-to-bank fueling issues because my when I had my original tune done at Cmotorsports Seth had a heck of a time getting the trims on both sides to equalize....I'm wondering if this is causing the problems or if the drivers side bank just runs colder for some reason (the bent electrodes have me a little worried though), I've had ZERO oil or coolant usage and other than the warm-start stalling issue that I've had from day one of the swap the truck runs GREAT (I'm hoping tuning gets rid of the stalling issue)

I'm also wondering if I had a bit of detonation from having to run 87 octane once a couple of weeks ago due to the lack of availability of 89 or 91......would that detonation have caused the gap to open on the plugs and the electrodes to shift sideways ???...if that is maybe the case I can see the plugs getting fouled out from the too-wide gap of the plugs after that

 

I highly doubt that running 87-89 octane would cause the issues with the plugs you described. Not sure what would, but I wouldn't think its pinging from low octane gas.