1.) Uninstall "Games For Windows Live" that came with GTA IV
2.) Download the newest "Games For Windows Live Marketplace" (Version 3.5)
(^^^ Don't worry about signing in once it's installed, it just needs to be on the PC ^^^)
3.) Install it, duh lol
4.) Tell GTAIV.exe to run as administrator (right-click, properties, compatibility tab)
5.) Download X---Live---Less v0.999b (without the dashes)
(^^^ Why is this being censored??? ^^^)
6.) Put the 2 .dll files from that download into the same directory as GTAIV.exe
7.) In Steam, right-click Grand Theft Auto 4 and then click properties.
8.) Click on Launch Options.
9.) Type in "-norestrictions -nomemrestrict" (without quotes)
(^^^ Allows graphics settings to be changed when there's more than 3gb of VRAM ^^^)
10.) Have fun. (hopefully)
I hope you find this useful