Bouncing idle and stall only on start

[thefrog1394]

Prefacing this: I've searched and haven't found any resolved threads

1991 318i. When I start the engine I get a rough/bouncing idle and usually a stall. After about 20 seconds the engine runs perfectly. Completely stable idle. (This to me rules out vacuum leak or idle control valve). Not a cold start issue because as soon as I shut the car off it will do the same thing upon restart. Any ideas?

[deansweet]

Fuel pump, fuel filter, fuel pressure regulator, crank position sensor?