Maine had even more of a three-way race in 1992: Clinton got 38.77%, to 30.44% for Perot and 30.39% for Bush.
Montana's performance in 1992 was very similar to Nevada's, where Clinton got 37.36% to Bush's 34.73% and Perot's 26.19%.
Had Perot not been on the ballot in 1992, I estimate that Bush would have carried Montana by 52.7% to 45.4% and Nevada by 50.9% to 46.5%, while Maine would have been too close to call.
I think the assumption for '92 is that if Perot had been out for good, that most would've voted for Bush, Sr. (since it is apparent that Clinton, in a lot of instances, only held roughly the same, sometimes less, sometimes more, of Dukakis's voters), but I still think in a head-to-head matchup, Clinton probably would've eked out a win (because a lot of the Perot voters either would've stayed home or voted for Clinton in protest).