Crowley

It will depend on what mods you use in your game,  but i suggest installing only what you consider essential and backing up that folder.
Useful if you decide to use a completely new car pack,  try out some enbs or if you start experiencing frequent crash problems.
 
That way you may only spend 3-5 minutes just copying tested and preconfigured files/folders over.  Rather than reinstalling and tinkering settings for 20min or more, a lot more. 
 
 
My personal method:
 
1)  I start off with the base GTA IV installation from steam,  so no testing needed.  Your game, video, sound options are saved somewhere else so it doesnt matter if you frequently delete/replace your GTA IV game folder.
 
2)  The next step is LCPDFR because it really is the major component.   Install that onto GTA IV and test a bit in game to make sure it is relatively stable.  And also set up options in the ini for callouts/scenarios/keybinds however you like them.
 
3)  ELS 8 is a requirement for me.   It is very easy to install which is great for testing.   I usually add only 1 or 2 modded vehicles to test and familiarize with the settings.  Limited configuring because your settings will change based on what cars you use.  (i revert the vehicles.img to default once i finish testing) 
 
Test a bit more for reliability and after all that i backup the entire folder.  So now i have a preconfigured GTA IV + LCPDFR + ELS 8 that i know will always work and rarely ever have to install these individual components again!  Just about 5 minutes(slow HDD) to copy it over and replace any bad installs.
 
At this point it is plug and play whatever you want.  Put in cars using OPEN IV or SPARK.  Most scripts i use simply require you to copy the script folder into GTV IV.  This is also very simple to deal with and troubleshoot if needed.
 
(another convenient option is to put in scripts you are familiar with inside the backup.  I like using the TowingScript and very rarely have issues with it.  I could include it.... but i personally like to keep things simple and basic.  I dont bother with any other scripts in my backup.)
 
So 5mins for LCPDFR+ELS 8 recovery.  Anywhere from an extra 3min to 15mins for scripts,  adding cars and how picky i am with customizing each ELS vehicle slot..
 
This makes it much easier for me to get back to the game and enjoy it for as long as possible.  At the very worst,  you would have 15gb of the game you are using and 15gb of backup.  30gb isn't too bad to save a lot of headaches.
 

 
 
The only arrogance i see in this topic is from you.
 
No one has all the answers. Nobody will have the exact same hardware, software, driver settings, adware/spyware whatever crap you can name.
 
Other users and the devs will try to help in what way they can. That is all we can do. Your post is the only disruptive one in this thread. Being constructive is giving tips, troubleshoot for other users or give as *detailed* bug reports as you can to the Devs.
 
It is that simple. If you don't get it and want to leave, good on you to figure that out.

Fixed it, apparently windows thought there should be duplicates of trainer.ini but then trainerini.ini
 
Topic can be closed

If you don't care about MP, use xliveless, I get about 25 extra fps with it.

I use xliveless, because it gives me like 20 extra fps, Try redownloading the DirectX End User Package again.

1.) You must remove dsound.dll or xliveless.dll. YOU CANNOT HAVE BOTH. It is recommended you use Dsound.dll. This allows you to play multiplayer.
2.) Please download this: http://www.microsoft.com/en-us/download/details.aspx?id=35
3.) Launch GTA IV and press ALT+P. This will launch LCPDFR.
4.) Have Fun!