Vacuum Leak?
 

My "Ninety-Eight" engine idles a bit rough but smooths out when driving. All vacuum hoses were replaced already. Any thoughts?

Over the years I ran into that a few times.And most often it turned out to be bad plug wires.
I'd look at replacing the plugs and wires.
If the wires are really bad,wait until dark,start the car and open the hood.The times that mine were really bad,it looked like a light show in the dark.

Thanks bob2231 for the advice and I'll be sure to check out those wires carefully next time I fire up the engine.