I was driving on highway doing 65ish with family in car when with no warning brakes engaged hard to point where i could not increase speed but barely made it to exit to pull off road.,. I called a wrecker and he was there within 30 mins. I got in car to put into nuetral and brakes where back to normal... Any thoughts or other experienced this?? Car is a 5 spd .. Im thinking master cylinder, btake booster or ads module? Where to start