cold start problems

[psychobabble]

I recently bought a 1990 525i with 94,000 miles - it's in fine shape except it has difficulties starting on cold mornings. Specifically, more often than not, it won't hold an idle and will stall out within seconds. This will repeat ad nauseum until finally it will hold the idle, very rough, however, until it warms up at which time it will run just fine. Any ideas? Oxygen sensor perhaps? Thanks.