I have a 95 olds and it had a problem like your , I was losing coolant and did know why . I thought it was intake gasket so I bought a plentum kit....what you have is an upper and lower intake. The lower is aluminum and there is a 3/4 tube sticking up on the driver side of it. That is for the egr valve. There are water jackets on both sides of that. What happens is this , the egr sucks hot gases out of the motor ( upper intake ) and reburns the gases.the tube gets so hot it melts the plastic upper intake , because the tube it the same size as the hole in the upper intake , and then it will pop holes between the water jackets and the tube allowing coolant to be sucked up and then burned . That's why you can't find it... That is if you don't have puddles under the car. The fix is to by the upper intake kit , it will come with the upper intake manifold , gasket, and a couple of different sized tubes so you can take out the stock one and replace it with a smaller one that will not touch the sides of the upper intake and cause it to melt again...it is very easy to do and it only takes a couple of hours to do.... the kit is about $120.00.