My '91 740(non-turbo) is experiencing idle problems when engine is cold. The engine is slow to start and stumbles when first started and will almost immediately die unless accelerator pedal is depressed. With the accelerator depressed, it will continue to run and the idle surges up and down for about a minute or two until it will finally idle at about 600rpm with no accelerator. The throttle body has been cleaned and drivability improved but cold idle problem remains.