This is from the Port Authority of New York and New Jersey website
http://www.stewartintlairport.com/CommutingTravel/airports/html/ewr_connect.html
EWR to JFK
Service Approximate Frequency & Travel Time
Airporter (Princeton Airporter)
1-800-385-4000 or (609) 587-6600
$24 Frequent service
7:00 AM to 5:00 PM
75 - 90 minutes
AirTrain Newark to NJ Transit or Amtrak to 34th St/NY Penn Station. Connect to NYC Subway A Train to Howard Beach. Connect to AirTrain JFK to terminals.
Newark Airport Express to Park Avenue and 120 E 41st Street near Grand Central Terminal in Manhattan. Connect to New York Airport Service Express Bus for JFK.
Newark Airport Express Bus: (212) 964-6233 or (908) 354-3330
New York Airport Service Express Bus: (718) 875-8200
Newark Airport Express Bus: $12
New York Airport Service Express Bus: $15 AirTrain: 6 AM to 11 PM - Every 4-8 minutes; 11 PM to 6 AM - Every 12 minutes
Newark Airport Express Bus: 4:00 AM to 11:00 PM
30 - 60 minutes
New York Airport Service Express Bus: 5:00 AM to 10:00 PM
45 - 65 minutes
Newark Airport Express to Port Authority Bus Terminal 42nd Street and 8th Avenue in Manhattan. Connect to New York Airport Service Express Bus for JFK.
Newark Airport Express: (212) 964-6233 or (908) 354-3330
New York Airport Service Express Bus: (718) 875-8200
Newark Airport Express Bus: $12
New York Airport Service Express Bus: $15
Newark Airport Express: 30 - 45 minutes
New York Airport Service Express Bus: 5:20 AM to 8:40 PM
65 - 85 minutes
Taxi (Flat Rate)
Go to Uniformed Taxi Dispatcher
$85.00 plus tolls On demand
75 - 90 minutes
Private Limousine/Van Service
Go to Ground Transportation Information Counter in Airport Baggage Claim Area
Prices vary On demand
75 - 90 minutes
To Macula: Options for travel from Newark Airport to JFK