1994 Lincoln Cont’l V-6 3.8 122,220 Miles?

Could be a air pocket forming under the thermostat, which causes it to hang closed sometimes. Take it out and drill a tiny hole in the part where the coolant pes, that will allow the air pocket through, but allow only a trickle of coolant. I think Ford had trouble with the head gaskets on some of the 3.8l/4.2l which could be contributing to the problem