Ad41 Engine intake getting hot. HELP

I have a AD41 engine and on the intake there is a nipple where a smaller plastic hose goes from the nipple to another nipple by the fuel throlttle area. Sorry I'm a true beginner on diesel. Here is what happened. I bought the boat recently took it out and it worked fine then on the 4 th trip or so just stated heading out and was at a good speed and all of a sudden lost half power. I opened up the hood and saw the hose melted off. It lost about half power at least and was putting black soot in the water with some black smoke. I replaced the hose and took it back out and it happened right away and still had the power loss. It idles fine starts easy and oil pressure is good with water temp. The location of the nipple on the intake gets hot enough to burn off the paint. Does anyone know what this could be. The only things I have done was lower the idle for trolling and did oil and all filter changes. I've since put the idle back to dealer spec not knowing if that could have any issue on this. If anyone can help it would be greatly appreciated. Thanks

Bilbo67, I am a little confused about the part you are referring to. If you could send some pictures or part numbers, it would help.

Ok I'm going to try and figure out how to upload a pic to this post it's the only plastic line coming of the intake

Air hose from manifold to injection pump is required for injection pump operation. With this hose melted or broken/cracked, injection pump will not deliver enough fuel. That is why you lost power.

Buy handheld laser thermometer and measure the actual temperature of the intake manifold. This area has only air in the manifold, which is 60-80F higher than ambient in worst case. So it should not melt anything.

Yes that is the part location I'm talking about Stringer but I did replace the hose and when I got out of harbor I went to put a load on it and it felt the same. I looked under hood and hose had already melted. It does not overheat it on trailer just when you put the throttle to it. Once I replace the hose the black junk disappears when running on trailer but again it will just burn the hose when it revs up. Do you know what can be causing the intake to get this hot?

Maybe leaking intake valves? combustion gas escaping to intake side. Or blocked cooling circuit on the head. How hot engine room you have, maybe you dont have enough fresh cool air to cool things down. If the paint is burning away you have serious overheating and should stop using the engine.