Ok, reading through the whole thread again I have a new hypothesis.
**Please don't think this is my idea but something just clicked as in my head and finally made sense to me.**
Ok let's say I have a cracked cup, blown Orings on one injector. That makes the coolant leak around the injector, run down into the oil return in the head (under valve cover) and go straight into the engine. I say this is not original ad I'm sure someone has already mentioned this scenario but it just clicked for me. That would explain the sludgy oil as the oil temp made the coolant boil once it went back to atmospheric pressure causing the sludge buildup in the intake via the CCV. Also the "coolanty" oil could make the injectors behave strangely, intermittently.
Also if I had a bad oring and it dumped mostly fuel into the oil that would account for weird non coolant liquid that drained out of the oil pan with the oil as the coolant loss could have just been evaporating with the heat of the running engine.
And when i pressurized the system I could have made a slight leak worse thereby seeming like a much worse problem.
more or less what I've been saying. Most of the time when a failure occurs shortly after a repair (in your case o-rings/cups) that is what I would look at first, unless you know that the engine was run hard, etc. These are really stout engines (B10 life = 250k miles, B50 life = 350k miles conservatively). Unless you ran with a heavy tune or did something silly I doubt the engine is blown.
By pressurizing only the coolant side, you may be getting a bigger leak at a cup/oring than if the oil side (10-100x more pressure than the coolant side) was pressurized by the HPOP. Once the engine is shut off the HPO goes to zero, along with the fuel pressure, but the coolant stays pressurized until it cools off allowing the coolant to flow past the now zero pressure fuel and oil sides.
This could also be the situation with the oil cooler. zero pressure on the oil side allows the coolant to flow directly into the pan, whereas if the engine was running you'd have 60psi oil at the cooler holding back 10 psi of coolant pressure.
Remember.... coolant 10psi, fuel 70psi, and oil 600-2800 psi depending on load when running.