Recently purchased '88 528e (145k miles) has intermittent hard start and idling problems. It is usually OK with great mileage and decent acceleration, but occasionally (1 time every 2 weeks or so) will be hard to start and will run very rough until warmed up. Sometimes will be OK after 2-3 restarts rather than wait to warm up. Have put in new plugs, rotor, cap, air & fuel filter; 1 tank of Techroline to clean injectors; cleaned ICV with carb cleaner; cleaned fuses.
Shouldn't most hard start/idling problems be more consistent (vacuum leaks, bad pressure regulator, bad sensors, etc.)? Or are most of the problems encountered usually intermittent? Any ideas what to look for?