Cool - I'm not alone!

 

IMHO the antenna booster might not be the answer is you are getting perfect signal with the engine off. This seems to be in interference problem not a reception problem. Yeah with this age of truck a floating ground is a potential, stuff rusts or comes loose. You might want to check for that also before spending for the capacitor. Mooney's right about AM, its really all I listen to myself.

 

It could even be the antenna itself isn't grounding well. It may be grounding through the radio, and as we all know the ground signal in most vehicle is pretty dirty by the time it reaches the antenna. Also if you had the wire replaced and they were cheap (I'll routinely pay $60 ~ $70 a set for them to get quality ones) they may not be suppression wires.

 

Yes, you are probably correct - I did not specify "suppression wires" so I really do not know what was put on. Pretty dumb, huh?

 

I thought from your post that you got the new plug wires after the radio problems started and it did not solve the problem. If your radio was fine until you got the new plug wires no doubt they are the culprit. They do need to be supression wires and you need good ones for many other reasons as well. Get the best ones you can afford.