Gore was a terrible candidate.
If he would have won his home state of Tennessee he would not have had to worry about Florida.
It was because of Gore that 2000 was even close. You have to remember that he trailed Bush throughout most of the campaign. It wasn't until the fall campaign when he really began to turn things around. Okay, Gore was stupid to not campaign with Clinton, but other than that, he ran a really good campaign.
Anyway, Gore would surely have won without Nader in the race. At least a few hundred would-be Nader voters would still vote, and would vote for Gore, in Florida.