Rough Idle/Stall in cold weather

[pstubler]

I have a 97 Windstar with 3.8. Last winter during especially cold weather it was hard to start and stalled until warm. The check engine light came on with an EGR warning (I cannot remember which). After some investigation I replaced both the DPFE and the solenoid. (Actually, I only replaced the solenoid because when I was checking the vacuum hoses I accidentally broke the mount for the solenoid. Ooops!) Anyhow, the problem went away, but incidentally the weather was getting warmer. Well winter is here again and so is the problem.
Some observations:
Once warm, its OK.
Overall milage is about normal (slightly lower than normal).
The exhaust smells really rich when cold.
No check engine lights.
The actual EGR valve seems to work OK.
The temperature sending unit appears to be functioning.
Any suggestions?