I don't often drive my Montero down to the city...but when I do I run into a strange problem. I am dropping from 9200 feet to 5200 feet in about 25 miles. Thus, almost the entire trip is down hill.

Yesterday the temp was 30-36 deg F.

The truck won't stay warm. The temps can get so low that I don't even get heat from the heater. At idle it will enter the cold loop where it keeps the idle higher than normal.

Before it gets really cold, anyone have any ideas on how to keep the truck warm? I could simply block part of the radiator for the drive down and pull it out for the drive up. Anyone have any better ideas?