Usually a front tire imbalance problem, with those described symptoms (out of balance forces approaching and driving the fundamental frequency of a front suspension spring/mass/damper mechanism, which is around 60-70 mph for most cars), but maybe a tire out of round, or having broken cords from pothole impact? Had that once, ended up with a bulge on the inner side of one tire.
Change the fronts to the rear and see if the symptoms change or go away.
Through the years, I've found that Alfa steering feel is pretty darn sensitive to front tire balance, having sometimes to go back for a redo, making the operator tighten up the machine readings. Sometimes "good enough" is not good enough in such direct steering.
One reason I think I would not like electric steering, as when the Alfa steering wheel is tremor free because of fine wheel balance, etc, it has great feedback, as compared to most of the new electric systems with their relative numbness, so I've read.
1989 Milano, Shankle Sport
1991 164S, stock
1994 164LS (~Q)
1972 Morgan 27
previously owned since 1964:
62 Morris MiniMinor 850, 67 Austin 1275 Cooper S (Downton 3/4 race), 64 Giulia Sprint GT (1st red one made), 72 Fiat 128 Sedan, 75 Alfetta Sedan, 78 Alfetta Sedan, 78 GTV, 81 GTV6, 86 GTV6
Last edited by Del; 05-25-2019 at 11:10 PM.