For people who have never played GTA IV, the script for the last mission is tied to framerate and you can't complete it if you run the game above 30fps. And even with the fps cap it's RNG on PC
Install GTA IV via steam / rockstar launcher, move the game directory out of the default location so it doesn't auto-update, use IV Downgrader to downgrade to 1.0.7.0 which installs a bunch of fixes, and boom
>>714091339 tried to do this too my gta 4 just crashed after loading screen which was fusionfix problem which I deleted and the game still had micro stutters