Oh JavyPro,
I'm sorry bro. I had something different but kind of like that happen to me too. I turned out to be that I didn't fully torque the intake manifold.

But yours sounds like something different all together. Have you tried a block tester? I don't know if it helps you now but it detects combustion fumes in your coolant. You have oil in your radiator, you will have combustion fumes no matter what. Time for a new set of heads? Clearwater?

89 Raider - V6, Automatic, rear LSD, A/C Retrofit, Cruise Control Retrofit.