Coolant leak

I bought a used 97 windstar with a 3.8 V6 with 136,000 miles on it. I noticed a coolant leak (around 1/2 cup) in the lower intake manifold area (above the cylinders closest to the firewall 4,5,6?), right above timing gear cover. This happens after the engine cools down once a week. I changed the coolant one month ago. Could it be that the previous owner added "stop-leak" additive before? Is this a small problem that will become big? Should I be concerned now? What can I do to fix it for good?

Common coolant leaks on post '95 model years.
Lower intake manifold gasket, can leak into the intake and into the cylinders.
Timing cover gasket, can leak into the engine oil....major repair.
There is a bypass that goes from the top of the water pump, has a rubber hose elbow, which connects to a metal pipe...which goes into the lower intake manifold. This pipe passes through the lower intake manifold, to the other side of the engine. I have one that I bought from Rock Auto, but have not installed it yet. This is another possible leak.

Head gaskets are not as high of a failure item on the post '95 windstar, if the engine has not been overheated due to another failure.

Coolant leaks need to be repaired ASAP as the more dangerous leak is the leak into the engine.
It is very important to monitor the overflow bottle to make sure that it is not dropping in level over time.
Left uncorrected, coolant into the engine will cause major damage.

You can take a sample of engine oil and send it in for analysis.
Blackstone Labs will send you the sample kit and mailer for free, and the testing is not expensive.
www.blackstone-labs.com