shutting off.

my 1988 biuck regal limited with a 2.8liter. when i am sitting in traffic for a period of time or maybe 3-4minutes. the car shuts off. it cranks right back up. the car drives light a champ when criusing on the street or freeway. the car dont always shut off when sitting in traffic. also i have two more questiom. 1. when i am driving sometimes the brake light come on an the cuts off. 2. sometime the car will not turn over. i know why it wont turn over. the the gear selector is not always in park. the needle is in park but the transmission is not in park. i have to wiggle the the selector to get it to start. does this car have a shifter cable or what is it i need to replace to fix this problem or should i not worry about.