Join Date: Jun 2000
Location: Used to be on ships looking for oil and gas; Uruguay, Malaysia, Turkey, Nigeria, Libya, Egypt, Norway, Scotland, India, Congo & Angola. Agreed to CC rules
Programs: AC Aeroplan, Porter VIPorter, AS MVP, AF/KLM Petroleum Club, BA Blue
Posts: 1,187
I'd say it will be tight, not just the airport, security and US customs, but getting to the airport from downtown with less than 2.5 hours before flight time. One traffic slowdown between downtown and the airport and you're completely screwed.
If you were at the airport with 2.5 hours in hand, I'd say you'll be fine. 2.5 hours from downtown, not impossible, but you'll need to be lucky. Hopefully minimal traffic, carry on bags only, online check-in and preprinted boarding passes. Make sure you grab a blue US Customs form and have it filled out before the US Customs desk too.
Good luck