You need a Choke on a cold gasoline engine, so get a manual choke cable in the cab
Good read here on 2150 and 2.8l:
https://www.therangerstation.com/forums/index.php?threads/1984-ranger-2-8-motorcraft-2150-jets.98716/
The 'idler' screws ARE the AFR adjustment, they are always feeding fuel into the engine, so you can Richen one side by turn that sides screw out a bit
You need a week or so to get readable color on spark plugs tips unless you are getting oil in the cylinder, then you know right away, lol
A vacuum gauge is a very good tool to have and to use on any gasoline engine(carb or EFI) for many test and tuning