1989 325 radio crakles until car body is warmed up

Hi Kids,
My 1989 325ic radio crackles and pops (as loud as the music) and the sound has obvious distortion on my drive to work in the morning.
I listen SOLELY to a mp3 player running thru a cassette
adapter. (but the crackling is still there on am/fm/weather)
After work driving home after the car has been sitting in the San Diego sun all day and car itself is hot . . No Crackling or distortion, plays loud and clear.
If it's been raining, or I just washed the car, forget it, the crackling and engine buzzing is way louder than any program material.
A few Facts that may or may not be helpful:
The antennae doesn't go up when I turn the radio on.
There are no blown fuses in the fuse box
Heater fan has no audible interference
The car spends the night in a nice dry single car garage.
There's no leaks or holes in the conversable top or trunk.
I'm assuming I have a ground problem or short somewhere that fixes itself when the car body has warmed up. Possibly in the trunk amp harness (I think there is a trunk amp, YES?)
TIA for any suggestion O
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