So i just installed the lspdfr mod, and whenever i am driving around, on or off duty, or even standing outside the police station, hostile NPC's spawn a few blocks away and drive to me and then attack me. They follow me even into the police station, and no matter what i do they follow me and shoot at me. They keep on spawning. How do I stop this?

Are you by any chance at that point in the story where Michael and Trevor are banned from Los Santos? If so, you need to play past that section or load an earlier save where they are still allowed into the city.

 

Else, check if you have a trainer installed and a key-press is making this happen.