Mr. Squirrel wrote:

"It's an auto trans so I don't have the luxury of revving the engine and feathering the clutch to get across the intersection.  A bit of an inconvenience to myself and those behind me."

Yes you do!  Just keep your foot on the brake and rev it up!  This is much easier with an automatic than with a manual.  I've driven a couple miles this way when my van refused to idle at all--you only need two feet to keep it running.  With a manual you'd need three feet!

You probably have a vacuum leak that either seals up when warm or doesn't bother a warmed up engine.

Stuart