Over heating 99 Villager

Hey guys, I need some fresh ideas,
My 1999 Mercury Villager has an overheating problem. There’s no water in the oil and no white smoke coming out the tail pipe. So far I have tried two different engine head gasket stop leak products, No help. Replaced thermostat, (even ran without, no joy)
I pressure tested the cylinders and got around 180 psi in all six.
Next I pressure tested the radiator and cooling system, the heater core leaked so I bypassed it. Found and fixed a leaking lower intake. No joy. Tried a new radiator, no joy. The radiator fan nuns fine.
Pulled out and made sure the water pump is good and removed the thermostat again. Thought I fixed it!
I ran it to the gas station yesterday with a radiator flush solution and water in it and it ran fine.
Today I flushed it out and filled it with antifreeze. Then it over heated again! I put a funnel in the radiator fill point and watched as fluid and bubbles came out. I think it must be a cracked block or something. Leaks exhaust into the cooling system when it gets up to temp. Any ideas? It’s driving me crazy now. I may try a more expensive stop leak product.
Thanks for your help!

Stop leak products are only a very temporary Hail Mary to get it someplace to get it fixed.

Exhaust in the cooling system has to be from a crack somewhere. Your next test is a leak down test. Get that done, and it should point you to the real problem.

Chase