when driving the trunk light comes on randomly. then it will turn off. and it does that the whole time i drive. anyone know if there are sensors some where that might need to be tightened down?

You will most likely need to have the trunk latch assembly replaced.
The switch is located inside the latch assembly.

I replaced the trunk latch assembly, but, the dash light is still on. Any suggestions?

If you close the Latch manually does the light go off?
If not then look at the wiring diagram and try to track it down.
http://www.volvotechinfo.com/WD123/
I forget what year yours is just click on your year on the list.