91 318is won't hold idle after cold start?

[E dub]

I'm having a little bit of an issue with my 91 318is. If the car has been sitting and it's cold it won't hold idle unless I keep the throttle pressed for a couple minutes until the car is warmed up. If not, it will die out. Once the car is warmed up it runs/drives and idles great. I've searched and can't seem to figure what the problem is?