[merc81]

Yea, I'm not sure what you mean about the intake not holding vacuum also? How about pressure testing the cooling system? Pump up the system to about 15, 18 psi and see if it holds for a few hours. You need to do that when cold as the cooling temps of the engine when hot will go from pressure to vacuum (that's how the overflow tank works). If the head gaskets were bad, there should have been some gunk in the coolant lines and radiator---maybe flush the radiator out seperately? I'm thinking remove the radiator inlet and outlet hoses and use an outboard pump in a bucket of vingar to flush out the radiator?