I have a 89 GTA Trans Am and it is leaking somewhere behind the block, down the transmition onto the exhaust so it steams really bad. I just replaced the starter and broke an exhaust to manifold bolt and replaced it. The leak started after I put it all back together.

 

probably a valve cover gasket. Might be the trans dipstick too. Have to get under the car and have a look. should be pretty easy to see what its coming from

 

Could be the seal on the back of your intake too, you might take a look at that if all else fails