Our household now has three 200-series Volvos -- an '85, an '87, & an '89. I'm learning a lot from reading the Board and repairing these. I'm wondering what length of service life can be reasonably expected from certain components, such as:
-- Idle air control valve. I disassembled the one from the '85, w 228K miles, and found that it had craters in each of the 3 armature poles. The symptom was high idle speed, and was cured by using a known good one from the '87.
-- Ignition coil (In my experience, motorcycle coils tend to get weak after 20 years)
-- U-joints

Other questions for you old hands:

Why would the degree of brake boost be different in each of these 3 cars? Oddly, the newest one requires the most pedal pressure, and the old '85 the least.

The steering mechanism on the '85 has a little friction when rolling straight down the road, requiring more steering input corrections than the other cars. What should I check, and how?

--Phil Loizeaux