I have an early 1981 300SD with 250,000 miles. After I crank it in the morning, I have a slow idle. It has gotten progressively worse as the temp has dropped. It is now in the low 40's in the morning. If I don't give it a little fuel as I back out of the garage, the engine will often die. By the time I reach the end of the street, the idle is normal. Occasionally, the engine idle will hunt when the car is shifted into neutral. Acceleration is normal at all operating temperatures.

My other Deisel (1982 300SD with 248,000 miles) is not exhibiting this problem.

Any ideas?