The diverter valve for the injection pump on my '84 Regal's 3.8 litre is blown, so I am told. At idle it sits and vibrates and makes a low hollow vibrating sound.

Looks like replacement valves are pretty expensive, so I've considered removing the whole AIR pump all together.

I'm wondering if the lines running to the catalytic converter can just be capped off?

Also there's two electrical connectors that connect to the diverter valve....I don't suppose it would hurt performance/ECM if I just unplugged them and left them unplugged?

The AIR is used only at cold idle. I'm pretty sure it won't trigger a check engine lite. I would go ahead and cap the pipe to the converter.