[Diavolo]

Throwing my hat in there. Your drains in the lifter valley are plugged. Get a new intake gasket, pull the intake and, at minimum, run a rod through the valley drains. If it were me, I would probably pull the pan plug and wash out the lifter valley with kerosene and a stiff brush, then pour some fresh oil through the middle of the valley to make sure the cam has lube.

Then fill, run a sludge remover and drain again, then refill.