I always reconed the best volvo was the late 80's 240 with the K-jetronic system
Absolutly bombproof.
Only three "Weaknesses" that I can recall
1) Injector "O" rings harden alowing air leaks which can cause irregular idle. Attempting to adjust mixture without addressing root cause messes up fueling profile.
2) If oil changes are neglected the vapour separator and flashback surpresser cloggs up causing crancase presurisation. Oil forced out of the engine gets onto engine wiring and rots the insulation. Engine loom is however a "separate" section and can be replaced relativly easily.
3) front suspension spring pans can rot and fail (spectacularly) Volvo replacements are zinc galvanised!!