Could anyone tell me the symptoms of a bad manifold or riser or elbow? I have a 1983 citation open bow with 2.5l chevy omc i/o. I can idle fine in water but when i put in gear and accelerate engine bogs down severly and sometimes stops. My manifold and riser and elbow look very bad and deteriated. I also did a head gasket replacement cause i was getting water in oil. Engine doesnt seem to have a crack. Can these bad items cause these symptoms and water get back into oil if it is getting past seals from rot? Thank you.