If you're not using a mid layer between your wool base layer and your Shower's Pass shell, that's the problem. Sounds very counter-intuitive, but it's true, and a much better jacket also worn over a base layer but not mid layer will do the same thing. Invest in a cashmere sweater, or a fleece, or a softshell.

Your base layer's job is to move your sweat outward. Your shell can only let so much vapor out, and, once it's at its limit, this starts to condense into drops of sweat, and then it's trapped. You'll start to feel clammy, which is cold in its own right, and, when you stop, like for a red light, your body will try to produce more heat to compensate. An insulating layer puts an end to that, and helps deal with the sweat, away from your body, keeping you nice and comfortable.