kennebellgt

i have a 1989 5.0 and recently i installed a new deck in my car and after that my battery voltshave been fluctuating from normal to very low. when i start it up on cold starts it wants to die and after it gets warm it idles fine, but sometimes even when it warm it wants to die, i tried unplugging the constant hot for my cd player to the fusebox and it still does the same thing the battery guage drops and the car dies, any advice would be great im not sure if its an electrical problem or something else also car backfires pretty badly after 5500 rpms. thankyou for your time.

aode08

run another new ground wire to the top of your AC bracket bolt. They are $4 complete at autozone, with the connector already on the wire.
Use a piece of sand paper to clear the surface rust.

kennebellgt

the main neg cable?