Comments.
- Use the plastic floats, set FL to 29/32".
- 9-10" of idle vacuum & the fact that the engine wanted to die when you pinched off the PCV tells me what I suspected all along: the PCV pintle is not closing off at idle because of the low vacuum....resulting in a LARGE amount of air being supplied to the engine at idle......which is why the pri blades are nearly closed at idle.....
- A correctly working PCV supplies air at idle equivalent to a 7/64-1/8" orifice. Quite small. When the PCV does not close fully because of low vacuum, it supplies a HUGE amount of air.
- you can buy [ expensive ] adj PCVs. What I do is essentially put a washer or plug in the PCV hose that has a 1/8" hole in it. Fixed.
- I would try one of the other 6XXX TQs you have.