i just discovered another symptom! don't know if it's related but...
if i brake very hard the rpms go down slightly while at idle. so if i'm in park with the engine warmed up after test drive and 900rpm idle, then i press the brake pedal very hard twice in a row the engine rpm goes down to 700 (i'd say) and i can feel a hesitation. it doesn't die and goes right back up to normal, but it's just odd because i never noticed/cared about it before.
is this an indication of a power brake issue, a vacuum leak or just a normal way of reacting because i'm using up the available engine vacuum quickly?
just to mention the idle stall happens mostly while sitting at a light, just barely holding the brake.