I really don't believe it to be the valve cover gaskets. I have not only replaced them and added rtv at the front corners, but have installed new isolator washers as well. I originally had the pcv system setup correctly with a check valve installed between the intake manifold (ffim) and valve covers and then T-ed into the catch can and charge pipe (per IJ's diagram). On my first dyno pull, there was blue smoke on decel, but the turbo was leaking out of the compressor into the intercooler. I sent the turbo off for rebuild and this resolved the oil coming from the turbo, but I still had smoke on decel. I removed the catchcan, since all it was catching was moisture,removed the pcv setup and simplified it by T-ing the valve cover lines and running them directly to the charge pipe. There is now zero oil in the charge pipe, but my plugs get oil soaked after a single drive cycle. There is oil present on their threads, but the wire boots are all dry. Since I rarely drive the vehicle, and letting it sit for more than a couple of weeks causes surface rust to build on the cams, I pull the EFI fuse around once a week and crank the engine until there is oil pressure to keep the internals nice and lubricated. I don't like to just let the engine idle cold and dump fuel in the cylinders since my EMS is currently tuned to run pig-rich on warm-up. I can't see this being a problem other than excessive wear on the starter. However, if the valve stem seals are split and oil is leaking into the cylinders when it rests, perhaps the cranking of the engine is forcing the oil up into the plugs' threads?
Here are pics of each spark plug upon removal (less than 200 miles on them):
The top of the pistons are all black and shiny (basically caked with carbon and oil). I'm surprised that the plugs don't foul and misfire, but the engine actually runs great. So what's more likely, split valve stem seals or excessive crankcase pressure?