I was fixing the leaking antifreeze in the lower intake manifold on my 1999 Tahoe, 5.7 Vortec, 4x4 with 64,000 miles. After removing the upper intake manifold I noticed the top of the lower intake was covered with wet oily residue/carbon, do not believe this is right, please see attached picture. Is this normal, if not any suggestions on the cause?

When I removed the individual spider poppet valves from the intake ports they all seemed in place and tight. Removed the heads and had local engine rebuilder clean and inspect, he said all was good on the head and valves, replaced valve guide seals while it was out, they were dry and cracking. New gasket will be used when installing.

Thanks

 

That looks normal. For future reference you do not need to pull the upper intake off the lower to remove the lower for the truck, unless you needed to do something under there (like replace injectors)