Here's the situation. When I first start my engine and it's cool outside, the brakes work awesome. It feels like you could stop on a dime. Once the engine warms up, this goes away and brakes return to their usual selves.

I have new lines/pads in the front, and the system had fresh brakes fluid last year.

But I'm baffled - why would my brakes work so much better when it's cool outside and the engine is cold?

The engine temp has nothing to do with the brakes.

You probably have a brake pad that works better when cold and fade away a bit as they heat up. Try switching the pads for ones with a more aggressive pad compound. Also, when was the last time the brake system had a complete overhaul?

Ed

Last year my neighbour threw on new pads/lines/flushed out old fluid. Is that what you mean by a complete overhaul?

And the pads/lines were AC Delco ones as well....