Mopar 383 help please

I'll chime in with a couple of ideas. The slow return to idle can sometimes be indicative of a vacuum leak. You can spray carb cleaner around the base of the carb and where the intake mates to the cylinder heads while its running. If the engine slows down or stumbles when you spray the carb cleaner, you likely have a vacuum leak.

Make a homemade "stethoscope" out of rubber tubing. Place one end of the tubing in your ear and place the other end on the valve cover or valley pan or wherever you think the noise is coming from. Often, this will really help you pinpoint where the noise is coming frpm in a loud environment. After that, as said before, buy some gaskets and open her up to check the internals firsthand. Good luck.