Once the manifold's peripherals have been removed, take out the bolts and pry the intake loose. It shouldn't put up too much of a fight. Before you clean the cylinder head surfaces, place some cardboard or a towel in the lifter valley to catch any debris. Use some rags or paper towels to plug the ports and scrape until the surface is clean. Follow up with some brake parts cleaner and the engine is just about ready for reassembly.