This is from the Coach USA website: Coach USA's Stewart Airport Express offers fast, convenient transfers between Stewart International Airport and New York City! Timed to your Norwegian Air flight, the Stewart Airport Express is the only direct transit link between New York City and Stewart International Airport.
Take an Uber or Lyft or taxi to port authority terminal in NYC then Coach USA to Stewart International. Leave a ton of time ! Plan on 45 minutes from JFK to port authority .. then 90 minutes once you are on bus to Stewart International. Check Coach USA website for bus schedule.
JFK is in queens which is a borough in nyc but that bus goes to from Manhattan/Stewart. So, you'll need to take a cab, bus or train from JFK in queens to Manhattan first before you can get the shortline bus up to Stewart. Queens and Manhattan are both nyc but they are not within walking distance from each other by any means
Thanks! Your answer is awaiting moderation.