It's a pretty dead board but even if no one responds this topic will be archived for a few years so maybe it will help someone out down the road. I just got 100% on this and was having a problem because for a while I was stuck at 98% and couldn't figure out what I was missing. So here's a full list in case anyone ever needs it.
* 41 story missions passed
* 100 packages found
* 21 rampages passed (7 per island)
* 18 races won (6 per island); (F1 racecar unlocked)
* 100 taxi fares (Borgnine unlocked at 50, but you need the full 100 fares for 100%)
* 12 ambulance levels (health at safehouse at lvl 9, and infinite run unlocked at lvl 12)
* 60 firefighter levels (20 per island); (flamethrower at safehouse when all are done)
* 60 vigilante levels (20 per island); (for every 10 a bribe appears at each safehouse)
* demolition football - stats say 1 next to it in the menu, doesn't look like it can be repeated
What was tripping me up was I had done everything but assumed (and read) that only 50 taxi fares were needed since that's when the Borgnine unlocks. But I went ahead and did the remaining 50 since that's what was needed in GTAIII and sure enough I got my last 2%. Good luck for anyone going for 100%, the races are damn hard but still possible.