Off and on for the last couple of years and steadily more often this winter, when it is below about 10 degrees F outside, before my 08 Max warms up the power assist is basically gone. After it warms up for several minutes it's fine. Has anyone else had this problem. The car has 94,000 miles on it.

 

Been colder this winter than it has for many years.

Sounds like a problem with the vacuum assist chamber or its vacuum.

 

water in the brake lines?

 

Check vacuum, I 2nd DalastDon.

 

Sounds like the Brake booster. Usually it is a vacuum issue on older cars. Not too common on newer cars, but you never know.