We’re making an RP map named Wolf County, but we’ve had two persistent problems.
1 - It never rains. Ever.
2 - The map has no item or car spawns. This is intentional. However, when we spawn in cars and destroy them they never despawn. Their destroyed remains just stay forever until we restart the server.
Hm, I have also recently started an RP server and indeed have the same issues; altering the config to make cars despawn faster does not seem to work, and I did not even notice that it never rains until you brought it up.
However, I have noticed that changing the map to something non-RP returns things to normal; I know this does not help, but at least you are not the only one experiencing this issue.