ok, i've noticed that sometimes when i come to a stop and i'm lightly pressing the brake, my idle will be fine, but when i get to the light and i push the pedal down even farther it will drop my idle. more so when it's colder. if i sit there and idle and i push the brake pedal a few time in a row it will almost stall my car out. is this a bad booster?

 

yeah sounds like a bad booster or vacuum leak somewhere