1995 Ford Bronco Coolant backflow out of reservoir after sh

Engine Cooling problem
1995 Ford Bronco V8 Four Wheel Drive Automatic

I have a intermittent cooling issue. Sometimes after a bit of stop and go driving when I come home and shut off the engine coolant boils out of the reservoir. This doesnt happen all the time but every other day or so and dumps about 1/2 - 2 liters of fluid onto the driveway. There doesn't appear to be any leaks and system temp is average on the gauge until the coolant is low after 2 or 3 spill outs.

I swapped the radiator cap but nothing else. Need some guidance.

Thermostat?
Reversed hoses?
Air pocket in the system?
Heater core issue?

Jeff