89 325ix stalling when cold

Drove fine Saturday, but on Monday the engine would not start easily. I could get it to start by depressing the accelerator, and could keep it running with the pedal, but it would die if idled. If I keep it running long enough to get a little warm (couple of minutes while sitting parked), it will idle OK. I would suspect a stuck choke (open), but I didn't think these had a choke. All throttle linkages are moving freely.

Any suggestions?