E34 morning startup problem

I have a e34 520i (m50) the car started to have problems last winter
when it started to get cold it became increasingly hard to start in the
mornings and finaly refused . after changing coils,plugs unplugging
airflow (maf) nothing would help in the morning (would eventualy start
after a long time) finaly unplugged the crankshaft position sensor and
it started after about 2 seconds.( Ive been running likre this until
yesterday)I changed the sensor but it still doesnt want to start in the
morning unless I unplug it..(once warmed up I can plug it bak in and
starts and runs beautifuly) I dont know what else to do ´maybe change
the ecu or the relay (anybody have any ideas) thanks.Oz