Jbaj007 - the whole thing is mirrored on my home machine whoch, given the reliaboility of Microsoft products, gives me a 50% survival chance.
W126 - Hmmm, not sure on the V8 which inherently idles much more smoothly. I have the same problem on my 560SEL and there is a lot of discussion on this board of the problem with fixes including new injectors, injector seals, fuel filters, idle valves, spark plugs, spark plug coils, gasoline (!) and fuel distributor overhauls.
I've tried most of these (except the coils and distributor overhaul) and still have the stumble/roughness at idle - more like an occasional miss. Your mounts would have to be pretty much destroyed for you to feel them on the smooth, lazy V8. Unless your mileage is very high and/or you have fuel leaking on them, I doubt they are the cause. Maybe others can comment?