trans locked in park in cold weather

I have a 95 cutlass supreme, 6 cyl., auto trans., console shift., about 60,000 (yep, thats all). In cold weather, near or below 32F, I must warm up the car and sometimes pump the brake pedal, before I can get the trans out of park. Appears to be something with the trans gear selector and brake pedal interlock. I have been told I need everything from a brake overhaul to a new intake manifold gasket. Car runs just fine. brakes perform well with even stopping, trans shifts smoothly.
Most of the park lock safety features are triggered by the brake light switch first then move items to allow moving out of park. See if brake lights are really coming on when this acts up. If not - look to the brake light switch itself as the problem,