Chrysler Repair Questions? Ask a Mechanic for Answers ASAP
Hello and welcome to Just answer.com, Super mechanic here. About your vehicle.
It sounds like the power brake booster is going bad. You would want to make sure that there is good vacuum to it when that happens just to be sure. There should be about 18"
It may have gotten some moisture in it that is freezing, or it is a hard (rubber) diaphram.