[wiswind]

Your 2000 3.8L winstar should have a alluminum colored front valve cover (unless you replaced it and painted the replacement).
The improved valve cover from FORD was not painted.
This is the version with the improved baffel for the PCV valve.
You should be able to buy a new grommet for the PCV valve through Rockauto.

Please take note that it is NORMAL for some oil to be present in the intake.

A couple folks have had issues with broken springs for the valves.
Depending upon where the spring broke, you may or may not have noise.
You will need to remove the valve covers to inspect the valve springs.
One person posted pictures of their broken spring recently.
To avoid dropping the valve down into the head, this person rotated the motor to have the piston for the cylinder being worked on, in the TDC position......this is with the piston at the top most position.
You should be able to get the valve seals and springs through Rockauto.

I would also replace the valve cover gaskets......also available through Rockauto at good prices.
I would get the Felpro rubber style ones.
When you put the rear valve cover in place, use extra care to avoid rolling/pulling the gasket out of place.
The felpro rubber gaskets are to be DRY fitted.....no RTV.
A lot of oil can leak out the valve cover gaskets.

I am leaning more toward the problem being leakage and valve spring/seals.
Not leaning toward piston rings.

IMRC, if it was not working for a while, then it is likely that there is some crud built up that is causing the shaft to not turn freely.
Once you get it working freely, you should be fine.
As mentioned, if you remove the upper intake manifold to work on it......poke the EGR ports clear while you are there.
AVOID spraying cleaner down into the intake or having anything fall down into there as much as possible.....as it will be drawn into the cylinders from there.
Chunks could lodge in the valve seat and cause issues also.
I am well aware of the urge to make everything look squeaky clean, but that does not work well with keeping stuff out of on down in the intake.