Turned heat on, blew cold air, looked at temp and it was red line. on 2000 Ford Mustang

Engine started making noises like a large ball bearing in a tin can, I stopped. Steam pouring out the passenger side of the car (outside), opened hood, radiator was 1/2 cup low, reserve 1/2 full. Little bubbles were fizzing where the intake manifold meets the engine block. Once it had cooled, it did not make any noise and ran fine. A mile up the road, the temp was almost to red line again. No water spray on the engine, oil is clear. The radiator has never been flushed that I know of....where do I start? Has never done this or anything else before.

1 answer 3 comments
POSSSIBLE STUCK CLOSED THEMOSTAT WHICH IS BUILDING PRESSURE IN ENGINE CAUSING INTAKE MANIFOLD TO LEAK UNDER EXTREME PRESSURE.
Thanks for your reply. So, now does that mean the intake manifold needs to be replaced? There is a tiny hole - maybe a weak spot - and when the pressure built up a little piece blew out? Does the thermostat need to be replaced also...I had it replaced two years ago.
ck it out in boiling water and yes intake leak will need to be repaired also
I had the intake manifold gasket replaced. It's still leaking from somewhere because when I check the radiator level each morning (because it got hot again after that), I have to put about 1 cup of liquid into it. I can't tell if the leak is by the radiator or under where the hood meets the windshield wipers. There is no moisture on the floor inside; however, I noticed yesterday when I stopped, but still had the car running, there was a bit of "fog" on the inside passenger front window...now what, any suggestions? Thanks!