Matosh

This is how the vehicles.ide line should look like:
 
polpatriot, polpatriot, car, POLPAT, POLPAT, VEH@VAN, VEH@VAN_FO1_FO1, 100, 999, 0.2786, 0.2786, 0, 4, 1.5 ,1, truckfirefx+livery

After the scripts are reloaded, press ALT+P to activate the LCPD:FR again then press CTRL+P to force the duty, and then use SImple Native Trainer to spawn police vehicle and change to police officer outfit. Also, no, you are not going to be chased by the police if you switch to police officer outfit using Simple Native Trainer.

Delete xlive.dll then download this and extract .dll file to your GTA IV folder.

You don't mount the vehicles.img file, you open it with SparkIV or OpenIV.

Delete your savegames which are located in:
C:UsersUsernameAppDataLocalRockstar GamesGTA IVsavegamesuser_xxxxxxxxxxxxxxxx

'?do=embed' frameborder='0' data-embedContent>>

Run the game in the compatibility mode (not as administrator) and install this.

Go to your GTA IV folder > right click on LaunchGTAIV.exe > Properties > Compatibility and check 'Run this program as administrator', also do the same for GTAIV.exe, and un-check 'Read only' for GTA IV folder and sub-folders as well.

Delete those and extract scripthook files as I said in my previous post.

Press Shift when driving behind the vehicle you want to pull over. Breath-tests are not part of the LCDPFR modification it's an addon which can be found in downloads section under script & data modifications. ELS lights and sirens will not pull over vehicles like when you are pressing Shift.

Evidence are just pictures you upload to gallery. 

The reason why indicator script doesn't work is because of that fuel mod you have.

From:
 
polpatriot, polpatriot, car, POLPAT, POLPAT, VEH@VAN, VEH@VAN_FO1_FO1, 100, 999, 0.2786, 0.2786, 0, 4, 1.5 ,1, truckfirefx
 
To:
 
polpatriot, polpatriot, car, POLPAT, AMBULAN, VEH@VAN, VEH@VAN_FO1_FO1, 100, 999, 0.2786, 0.2786, 0, 4, 1.5 ,1, truckfirefx