Thanks, Haasman. I happen to have a new vacuum modulator that I was going to use in my 560 SL. I think its the same for the 560 SEC, so I'll try installing it and see if it helps. What are the symptoms associated with the b2 piston? Given the year of the car (1986), it would seem to be susceptible to this problem also. God, I wish I had been born rich instead of good-looking (LOL).
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.