Disconnect the coax from the radio and see if you still have a lot of noise. If it drops considerably , the noise is most likely coming from the fuel pump. The Ford pumps generate a bunch if wideband RF noise.
There is a cure for it I found a long time ago on an Explorer site but I lost the bookmark.
It involves building a homemade RF choke and splicing it into the power and ground wires close to the top of the fuel tank.
If the noise doesn't go away after removing the coax , it is either ignition or alternator caused.
If the alternator (whirring sound) , then you can buy a noise suppressor and install it.
If ignition (sounds like popping popcorn) replace spark plugs and wires with resistance types.
Archimedes screwed us !
I knew a blonde dyslexic agnostic insomniac - she'd lay awake at night, wondering if there really was a Dog.
2003 Ranger Edge 3.0 manual 2WD