And the saga continues........
That mileage was almost all highway, which prompted the question. Also, pulled a plug this morning and found a lot of black carbon deposits, typical or running way too rich. I'll try to find an indie shop to dial in the mixture setting. Thanks for the advice.
1986 560SEC: 150,000 miles, runs great, but I've got to sell it (too many cars for one man)
1987 560SL: 122,000 miles, used to run poorly, now (thanks to forum), runs great!
1997 GMC Jimmy: Turned out to be a turkey.
1989 T-Bird Super Coupe: 150,000 miles, still runs great. Ford got it right.