The intake manifold gasket is a common problem with the 90 degree GM engines. Replacing it requires you to bring the #1 cylinder to top dead center, then you have to very carefully scrape away the gasket material, being sure not to get any into the intake manifold itself. And you're going to have to look up the torque specs for reassembly. But, the short answer is that you're going to have to replace the gasket. Numerous resources are available online which go into detail on how to do this, or you can get a Chilton or Haynes service manual for that vehicle.
Diagnose the exact source of the leak then determine how to correct it.
under the intake manifold
They are under the intake manifold.
Drivers side of motor under the manifold.
There is two of them. They are located under the intake manifold. There is two of them. They are located under the intake manifold.
Under the intake manifold.
under he intake manifold
There are 2 of them, Thay are under the intake manifold. You will have to remove the intake to get to them.
under the intake manifold
There are two of them located in the block under the intake manifold.
Under the upper intake manifold. The upper intake manifold would have to be removed to gain access to the bank of injector poppets (the spider).
On the 4.3 engine it is located under the upper intake manifold. The upper intake manifold must be removed to gain access to it.
the starter is located under the intake manifold you can't miss it