After a few hours of playing on this (http://www.racedepartment.com/downloads/road-america.7095/) version of Road America that the AI were kinda bad on it. they had a zig zag problem on the first straight under the bridge and many boundary issues.
This also edits the fast lane so the ai are much faster (lap times are in the 2:06s at 92% AI difficulty).
I used the AI line helper app (http://www.racedepartment.com/downloads/ai-line-helper.16016/) to edit the boundaries.
Comment or message me if there are any issues with the AI and ill get on it asap
Improved AI for Road America 3.5 1.0
Assetto Corsa AI FIX for Road America