bubbling radiator

When I had a head gasket leak in a Mopar 2.2L (common problem), I got oil brown "mousse" in the top of the radiator and it would boil over after a 20 mi drive. There is a combustion gas detection kit to indicate a head gasket leak. I have one from "Cal Van" I bought at a specialty auto tools shop long ago. Tried it several times, but never indicated a problem. Didn't bother on my 2.2 L. Your problem sounds more like air bubbles in the system.