vacuum advice

[THENEWMEXICAN]

my 70' Blazer has a 350 with a Edelbrock carb and intake, mild cam, leaky automatic tranny, am/fm radio and a vacuum problem:

with the warm weather I noticed I was idling kinda high. figured I'd adjust that with a turn of a screw this week during my bimonthly look-around. BUT this weekend I have developed a vacuum leak:

symptoms:
1. hesitates and nearly dies when coming to a stop
2. at a stop dies and if it doesn't die sounds like it's going to and shakes.
3. runs fine in Neutral or Park without dosing some gas
4. hesitates upon acceleration

I've been reading all the posts I find about looking for vacuum leaks. BUT if you have some suggestions to lead me in the right direction I'd appreciate it.