From what I can tell, Bush failed to win over New Jersey independents and moderates. Also Bill Clinton was still a popular president.
This, people liked Bill Clinton and a lot of voters at the time didn't think there was much difference between the two so suburban voters stayed put for gore.
http://www.cbsnews.com/campaign2000results/state/poll_njop-.htmlGore won across all income groups and even 1/4th of conservative voters in the state.
In 2004 it was pretty different because 9/11 made a lot of potential bush voters who stayed out because of the good economy in 2000 to turn out in New Jersey.