Stalls immediately after firing on cold Morning?

I see this problem is reported multiple times by other owners of Solara/Camry models. The car fires fine when cold such as when left overnight but stalls and won't idle until it's warmed up for several minutes. You have to keep your foot on the gas and keep it revving at 2000+ rpm for a few minutes. Later in the day it starts fine. It runs fine once it's warmed up. There must be some sort of cold start sensor for the engine management computer or air restriction system for cold starting but our mechanic is clueless. Help!