1985 Nissan Sentra Hatchback Manual Idle Speed Is Much Too High

If you contaminated the throttle cable with lubricant, you HAVE to REPLACE IT. They are dry on purpose - so they do not collect and cake up with crud. This WILL cause it to bind, usually at partial or full throttle and then where will you be? ;) Get that fixed and then consider this:

If it is a carburetor engine (non fuel injection) likely cleaning the throttle linkages, springs and plates with carb and choke cleaner from a spray can will get the parts clean and loosened up. Some of those designs incorporated a weighted cam/ratchet to set idle speed when the engine is cold. As the engine warms, this cam/ratchet uses gravity and bimetal spring to fall back and allow the throttle plates to rest at normal, low, warm idle speeds. Crud, light rust, dry parts will prevent this from operating properly. I once serviced a Dodge B250 van for this very problem because *mud dobber wasps* decided to build a nest in the throttle linkages!