optispark (distributor) dies due to seal failure, and moisture entering the opti (or from waterpump dying and soaking the opti).
plug wires burn because the stock routing is awful, replacement of plug wires is also difficult because of routing.
spark plugs are past their lifespan, and replacement causes extreme bleeding of whoever decides to reinstall them. blood on exhaust manifolds causes strange smell when heated
already weak ignition control module dies when hot from heat soak from the head. car fails out of nowhere, and runs again after it cools off
back of intake manifold leaks due to poor gasket, you get oil everywhere, and have to put it back together with RTV
vacuum leaks from vac. hoses, incl. intake elbow are common just because of age, but also stress on the intake elbow from engine movement as the engine mounts become weaker
cooling system problems.. sludge caused by both dexcool and cooling system sealing pellets clogs stuff up, especially heater core, also in part because the waterpump (cam driven) spins VERY slowly at idle.
air in cooling system due to relative inability of the system to bleed itself.
also air dam falls off and causes overheating at highway speeds.
also ecm sometimes mysteriously stops signalling the fans causing overheating at slow speeds.
above cooling system problems cause extreme overheating and warps head(s), blows head gasket(s), causes unavoidable detonation and cracks pistons
cam bearing fails, and subsequent oil pressure loss causes other major interal failure.
pickup from oil pump falls off and subsequent oil pressure loss causes other major internal failure