1994 Honda Accord LX Sedan A/T

You may be my last resort on diagnosing & addressing this issue. At highway speeds, I get a rumbling, a wobbling that’s very noticeable, not only through the steering wheel but also to other passengers. It seems to be coming from the right side (the passenger side) though I’ve not been able to pinpoint if it’s originating from the front or the rear. Anyway, I’ve gone through the logical possibilities: the front brake rotors, the rear drums, the entire braking system; the steering rack, even close inspection of all suspension components with the car on a lift. No leaking, nothing loose. Everything looks good. I’ve also changed tires a couple of times, and had the car computerized-aligned, but all to no avail. To the eye, all the wheels spin perfectly round when the car is on the lift. But the shaking, wobbling, especially at 60mph or higher, is very disconcerting. What else might be the cause? Perhaps a broken engine mount? That might be my last thought unless you have another idea.