HELP!! with my 75 Dart

Go to a local car show and look for small block Mopars that are stockers [not street rods]. Find one with an old geezer standing next to it. He may have had it for decades and fixed it himself or knows a good mechanic. Then give him a pretty smile, which is easy for you to do. Then flash your tattoo. He'll tell you everything!!!

I don't know what has been changed over the years, but your engine came with a dual point distributor and a carburetor that probably had true idle idle jets. A few pictures of the top of the engine with the air cleaner off would help.