Terry,
As people have said this is a common and frustrating problem. It occurred with me right after rebuilding my 428CJ. This is how you correct the problem:
Buy Victor intake gaskets, not Felpro (they suck). Then go to the Dodge dealer and ask for rear end silicon gasket sealer, Cost 10.00, but it will be the best 10.00 you will spend.
Remove the intake, clean the area to make sure there is no
oil, use alcohol or similar product. Do not use the front and rear intake gasket strip, they are known to slip. Use the silcon you bought from the dodge dealer to fill the gap. Let it set up over night.
Also use the dodge rearend silicon to secure the gasket to the valve cover, then use bearing grease between the gasket and the block, then will create a vaccum and prevent leaks. You should be good to go in the morning.