I typically use starting fluid or brake cleaner to find vacuum leaks. Start the car, and spray the lines, go slow and don't spray anything that is hot or sparks. If you hit a leak in the system, the car idles up. If you suspect a spot, you can immediately go back over it and it will idle up again.

I've been reading the thread. But it sounds like you are mostly covered with possibilities.. But since my first post i the thread (#6) i said check for vacuum leaks. So I am glad you are.