Originally Posted by
corporate-wage-slave
You must check in your luggage, which at JFK they will do willingly, even on 2 PNRs. If you have to recheck your luggage at T3 I doubt you would make it. Or travel without checked luggage.
Good point. Baggage delivery is usually quite slow at T3 and it's a bit of a walk to the check-in area (first timers there may also find it somewhat difficult to find the departures area from the arrivals area) so a 90-min connection would be highly dubious unless the bag is through-checked.