RX300 cold start problem
 

I have a 2000 Lexus RX300 with 90,000 miles which I have owned since new. It has recently developed a tendency to stall when first started in the morning with ambient temperatures ranging 40-55 F. It starts normally, but then stalls when placed in gear. Sometimes it repeats this behavior two or three times. Once it is warmed up a bit, the problem goes away.

Hot starts are normal. Driving performance is normal. I detected no fault codes with my code reader. Any ideas on how to troubleshoot and solve this problem will be appreciated.