[danford1]

I have a 91 with 5.0 HO. Mine leaked just like yours.
It was the rear portion of the intake manifold gasket. It was dried out and popped out of place. I fixed mine . Not hard if you have done this type of work before. If you are a first timer, better get a few pointers from a mechanic.
I never use those cork or even rubber end gaskets. I always use a bead of silicon. Just clean both the block and intake with brake cleaner to remove all traces of oil. Run a bead about 1/4" in diameter on the block and on the intake. Wait about 20 minutes for it to tack up. Drop manifold stright down and torque bolts. I use long bolts with the heads cut off as alignment pins to slide the manifold down on. Then just unscrew pins (headless bolts) and replace with the intake bolts. 4 pins is all you need, or just 2 in opposite corners.
Let the silicon squeeze out and dry overnight. Next day trim up with a razor blade if desired. I use all colors of silicon. They all work just fine.
Cheers.

Danford1