Hello, from Michigan and own a gray 1990 929S with 155k miles. Bought it in June of 2009 with 147k miles from a guy named Dave that I am now 100% sure knew 98% more about the mechanical condition and repair costs than he let on. It was very clean for being a Michigan car. Though it was bought and lived in Texas for most? of its life.
I found out after I bought it that it needed WAAAY (waaay) "WAAAAY" more than was originally apparent. The previous owner did no maintenance. The cooling system was in abysmal shape, but I didn't find that out until after the water pump blew during a 25 mile drive in an extremely heavy down pore. That took out the weak left bank head gasket. I had to much money into the car all ready to call it a wash (front/rear brakes, exhaust repairs, 2 tires) so I did a complete head gasket, upper end gasket, water pump, timing belt job, and recored the brass tank model radiator since it was corrosion plugged. Took me 30 days to complete the job because I could not afford to break a single thing and the engine had not been cracked open since it was made. It was absolutely a restoration job rather than a repair job.
As a side note, not that you 929ers don't all ready know this, 929 parts are next to IMPOSSIBLE to find, when you do find them they are special order, cost more than could be imagined in a bad dream, and 33.00929% of the time they are the wrong damn part.
Good thing for this car that I like the beast for some crazy reason.
I have been here since day 1 of buying this 929S. Seems that this forum is the only real source of information on these cars (which has surprised me from the start since I expected there to be a lot of info out there).
Now that I have formed a long mental list of questions that I can't seem to find the answers to I plan to soon write that list out in a post here when time permits.