Go to my web site, look under Noise ID. I suspect it is ignition noise, and not injector noise that you are hearing. And you might have some cooling fan hash as well.
I have not way of telling what state of tune your Astro van is in, but to be sure that old plug wires, and wore spark plugs add greatly to the RF that is put out. New, properly gapped plugs, and new factory wires should quite things down a lot. After-market wires are not always the answer, by the way.
You could shield the wires, and I have information on that too.