Crawl down by the pedals and pull the kick panel off and look for the two little plungers that should be pressed against the brake pedal. I had the same problem after I changed the booster due to the rods being different lengths. I depressed the brake pedal with my hand and using a long screw driver I was able to push the plunger out. I found out one plunger controls the brake light sensor and park release and the other controls when the cruise control shuts off due to brakes being used. This could be one culprit.
Excuse my ignorance, but how are these two issues connected? I can see mechanical issues being affected by this, but I'm trying to think of how the brake lights would be involved. I'm just looking to learn something today.