Re the first call about the '92 Roadmaster’s intermittent noise: the guys are right about it being the self-levelling air suspension. I’ve got a '92 Chevy Caprice station wagon, with the trailer-towing package, and it does the same thing. I once pulled off the highway to nap, and that noise woke me up every hour or so. I don’t know why they didn’t run it through the ignition switch, so it wouldn’t drain the battery, but oh, well. The pump is in fact in the rear of the car, since it only works on the rear suspension.
I have a '99 Town Car with Air Suspension and the pump will go on sitting in the driveway, with no key in the ignition. ITis in the front of the car.
One solution would be to put a relay in the wire controlled by the ignition switch. Of course if there is an air leak you would best wait before driving off until the system inflates. But if there is an air leak, that needs to be fixed anyway.