Radio reception will get bad when you turn the key to the on position. but turn the key back to acc. and it plays fine.

 

I've seen very scratchy radio performance caused by poor volume control potentiometer. If adjusting volume slightly causes noise or fixes problem, the volume control is likely.

I've also had radios develop cracks in the connectors at the rear. In general, the easiest fix is to pull the radio and replace w/ a used or aftermarket unit. Repair is not worth effort or cost.

good luck